feat(starlette): Add http.route attribute

[alexander-alderman-webb]

Description

Set the http.route attribute on the ASGI server span in patches for Starlette endpoints.

Issues

Reminders

• Please add tests to validate your changes, and lint your code using uv run ruff.
• Add GH Issue ID & Linear ID (if applicable)
• PR title should use conventional commit style (feat:, fix:, ref:, meta:)
• For external contributors: CONTRIBUTING.md, Sentry SDK development docs, Discord community

[github-actions]

Codecov Results 📊

✅ 130404 passed | ⏭️ 7110 skipped | Total: 137514 | Pass Rate: 94.83% | Execution Time: 463m 9s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📈 +32113
Passed Tests	📈 +31482
Failed Tests	—
Skipped Tests	📈 +631

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2504 uncovered lines.
✅ Project coverage is 90.25%. Comparing base (base) to head (head).

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
+ Coverage    89.92%    90.25%    +0.33%
==========================================
  Files          193       193         —
  Lines        24908     25677      +769
  Branches      8986      9466      +480
==========================================
+ Hits         22398     23173      +775
- Misses        2510      2504        -6
- Partials      1430      1440       +10

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