bench: add ASOF join benchmarks

[Xuanwo]

Which issue does this PR close?

• Part of ASOF join support / Specialize Range Joins #318.
• Umbrella PR: feat: support ASOF joins #23738.
• Depends on feat: support ASOF JOIN SQL #23830 (and transitively feat: add ASOF join logical semantics #23829 and merged feat: add ASOF join physical operator #23828).

Rationale for this change

This is the benchmark layer of the ASOF JOIN stack. It keeps performance
workloads separate from the execution, logical, and SQL implementation reviews.

GitHub shows the cumulative stack because fork branches cannot be selected as
upstream PR bases. The isolated diff for this layer is:
Xuanwo/datafusion@xuanwo/asof-sql...xuanwo/asof-benchmarks

What changes are included in this PR?

• Add a dfbench asof command with six end-to-end workloads: ordered and
  grouped predecessor matching, wide payloads, descending successor matching,
  broadcast-side size asymmetry, and skewed equality keys.
• Stream output batches during timing instead of retaining result buffers.
• Assert that each workload plans to AsOfJoinExec.
• Add a physical Criterion benchmark for Int64, wide UTF-8, and dictionary
  payloads.
• Exercise both one and four left partitions while keeping the right input
  single-partitioned, covering broadcast build reuse and left-side parallelism.

Are these changes tested?

Yes:

• cargo fmt --all
• cargo clippy --all-targets --all-features -- -D warnings
• cargo run -p datafusion-benchmarks --bin dfbench -- asof --iterations 1 --partitions 4
• cargo bench -p datafusion-physical-plan --bench asof_join --features test_utils -- --test

The refreshed head completed all six end-to-end workloads with the expected
1,000,000, 1,000,000, 250,000, 500,000, 100,000, and 1,000,000 row counts. The
Criterion smoke run completed all six combinations of payload type and left
partition count. These debug/smoke runs validate the harness and are not
presented as performance claims.

Are there any user-facing changes?

This adds ASOF workloads to the repository benchmark tooling. It does not change
query semantics or runtime behavior.

This PR should be reviewed and merged after #23830. It does not depend on the
optional floating-point follow-up #24375.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 61.22159% with 273 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.51%. Comparing base (c4910e0) to head (1eb4760).
⚠️ Report is 20 commits behind head on main.

Files with missing lines	Patch %	Lines
datafusion/sql/src/unparser/plan.rs	51.16%	77 Missing and 7 partials ⚠️
datafusion/expr/src/logical_plan/plan.rs	59.48%	63 Missing and 16 partials ⚠️
benchmarks/src/asof.rs	0.00%	62 Missing ⚠️
datafusion/sql/src/relation/join.rs	83.33%	7 Missing and 8 partials ⚠️
datafusion/expr/src/logical_plan/display.rs	0.00%	10 Missing ⚠️
datafusion/expr/src/logical_plan/builder.rs	83.92%	1 Missing and 8 partials ⚠️
datafusion/core/src/physical_planner.rs	85.36%	4 Missing and 2 partials ⚠️
datafusion/expr/src/logical_plan/tree_node.rs	93.02%	0 Missing and 3 partials ⚠️
datafusion/optimizer/src/analyzer/type_coercion.rs	92.85%	1 Missing and 1 partial ⚠️
datafusion/optimizer/src/optimizer.rs	50.00%	0 Missing and 2 partials ⚠️
... and 1 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #23833      +/-   ##
==========================================
+ Coverage   81.47%   81.51%   +0.03%     
==========================================
  Files        1122     1124       +2     
  Lines      403629   406793    +3164     
  Branches   403629   406793    +3164     
==========================================
+ Hits       328866   331591    +2725     
- Misses      55510    55789     +279     
- Partials    19253    19413     +160     

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[github-actions]

Thank you for opening this pull request!

Reviewer note: cargo-semver-checks reported the current version number is not SemVer-compatible with the changes in this pull request (compared against the base branch).

Details

     Cloning apache/main
    Building datafusion v55.0.0 (current)
       Built [  62.343s] (current)
     Parsing datafusion v55.0.0 (current)
      Parsed [   0.035s] (current)
    Building datafusion v55.0.0 (baseline)
       Built [  62.047s] (baseline)
     Parsing datafusion v55.0.0 (baseline)
      Parsed [   0.036s] (baseline)
    Checking datafusion v55.0.0 -> v55.0.0 (no change; assume patch)
     Checked [   0.584s] 223 checks: 223 pass, 31 skip
     Summary no semver update required
    Finished [ 127.333s] datafusion
    Building datafusion-expr v55.0.0 (current)
       Built [  30.906s] (current)
     Parsing datafusion-expr v55.0.0 (current)
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    Building datafusion-expr v55.0.0 (baseline)
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     Parsing datafusion-expr v55.0.0 (baseline)
      Parsed [   0.077s] (baseline)
    Checking datafusion-expr v55.0.0 -> v55.0.0 (no change; assume patch)
     Checked [   1.217s] 223 checks: 222 pass, 1 fail, 0 warn, 31 skip

--- failure enum_variant_added: enum variant added on exhaustive enum ---

Description:
A publicly-visible enum without #[non_exhaustive] has a new variant.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#enum-variant-new
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.50.0/src/lints/enum_variant_added.ron

Failed in:
  variant LogicalPlan:AsOfJoin in /home/runner/work/datafusion/datafusion/datafusion/expr/src/logical_plan/plan.rs:301
  variant LogicalPlan:AsOfJoin in /home/runner/work/datafusion/datafusion/datafusion/expr/src/logical_plan/plan.rs:301

     Summary semver requires new major version: 1 major and 0 minor checks failed
    Finished [  63.674s] datafusion-expr
    Building datafusion-optimizer v55.0.0 (current)
       Built [  28.331s] (current)
     Parsing datafusion-optimizer v55.0.0 (current)
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    Building datafusion-optimizer v55.0.0 (baseline)
       Built [  29.321s] (baseline)
     Parsing datafusion-optimizer v55.0.0 (baseline)
      Parsed [   0.033s] (baseline)
    Checking datafusion-optimizer v55.0.0 -> v55.0.0 (no change; assume patch)
     Checked [   0.172s] 223 checks: 223 pass, 31 skip
     Summary no semver update required
    Finished [  58.661s] datafusion-optimizer
    Building datafusion-physical-plan v55.0.0 (current)
       Built [  40.448s] (current)
     Parsing datafusion-physical-plan v55.0.0 (current)
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    Building datafusion-physical-plan v55.0.0 (baseline)
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     Parsing datafusion-physical-plan v55.0.0 (baseline)
      Parsed [   0.153s] (baseline)
    Checking datafusion-physical-plan v55.0.0 -> v55.0.0 (no change; assume patch)
     Checked [   0.741s] 223 checks: 223 pass, 31 skip
     Summary no semver update required
    Finished [  83.128s] datafusion-physical-plan
    Building datafusion-proto v55.0.0 (current)
       Built [  57.281s] (current)
     Parsing datafusion-proto v55.0.0 (current)
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    Building datafusion-proto v55.0.0 (baseline)
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     Parsing datafusion-proto v55.0.0 (baseline)
      Parsed [   0.018s] (baseline)
    Checking datafusion-proto v55.0.0 -> v55.0.0 (no change; assume patch)
     Checked [   0.127s] 223 checks: 223 pass, 31 skip
     Summary no semver update required
    Finished [ 116.090s] datafusion-proto
    Building datafusion-sql v55.0.0 (current)
       Built [  45.124s] (current)
     Parsing datafusion-sql v55.0.0 (current)
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    Building datafusion-sql v55.0.0 (baseline)
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     Parsing datafusion-sql v55.0.0 (baseline)
      Parsed [   0.034s] (baseline)
    Checking datafusion-sql v55.0.0 -> v55.0.0 (no change; assume patch)
     Checked [   0.228s] 223 checks: 223 pass, 31 skip
     Summary no semver update required
    Finished [  91.611s] datafusion-sql
    Building datafusion-sqllogictest v55.0.0 (current)
       Built [ 105.680s] (current)
     Parsing datafusion-sqllogictest v55.0.0 (current)
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    Building datafusion-sqllogictest v55.0.0 (baseline)
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     Parsing datafusion-sqllogictest v55.0.0 (baseline)
      Parsed [   0.026s] (baseline)
    Checking datafusion-sqllogictest v55.0.0 -> v55.0.0 (no change; assume patch)
     Checked [   0.103s] 223 checks: 223 pass, 31 skip
     Summary no semver update required
    Finished [ 213.857s] datafusion-sqllogictest
    Building datafusion-substrait v55.0.0 (current)
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     Parsing datafusion-substrait v55.0.0 (current)
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    Building datafusion-substrait v55.0.0 (baseline)
       Built [ 333.602s] (baseline)
     Parsing datafusion-substrait v55.0.0 (baseline)
      Parsed [   0.018s] (baseline)
    Checking datafusion-substrait v55.0.0 -> v55.0.0 (no change; assume patch)
     Checked [   0.257s] 223 checks: 223 pass, 31 skip
     Summary no semver update required
    Finished [ 660.481s] datafusion-substrait