test(asgi): Remove transaction tests

[sentrivana]

Looks like the asgi integration itself doesn't have any span streaming branching, only the tests do.

Closes https://linear.app/getsentry/issue/PY-2679/remove-transaction-based-tracing-from-asgi

[linear-code]

PY-2679

[github-actions]

Codecov Results 📊

✅ 107780 passed | ⏭️ 5338 skipped | Total: 113118 | Pass Rate: 95.28% | Execution Time: 342m 25s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📉 -12704
Passed Tests	📉 -11280
Failed Tests	—
Skipped Tests	📉 -1424

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2241 uncovered lines.
✅ Project coverage is 90.55%. Comparing base (base) to head (head).

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
+ Coverage    90.30%    90.55%    +0.25%
==========================================
  Files          193       185        -8
  Lines        25601     23705     -1896
  Branches      9436      8734      -702
==========================================
+ Hits         23116     21464     -1652
- Misses        2485      2241      -244
- Partials      1435      1365       -70

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