fix(starlette,fastapi)!: Stop eagerly consuming request bodies

[alexander-alderman-webb]

Description

Read the request body in the event processor body and only rely on cached attributes.

The code to read the request body in StarletteRequestExtractor.extract_request_info() now mirrors _get_cached_request_body_attribute(), which is used to get the request for streamed spans.

Issues

Closes #7285
Closes #4827
Closes #4764

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

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[github-actions]

Codecov Results 📊

✅ 66169 passed | ⏭️ 3292 skipped | Total: 69461 | Pass Rate: 95.26% | Execution Time: 207m 34s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📉 -65991
Passed Tests	📉 -62152
Failed Tests	—
Skipped Tests	📉 -3839

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2261 uncovered lines.
❌ Project coverage is 89.49%. Comparing base (9a5e80e) to head (ac553cd).

Files with missing lines (1)

File	Patch %	Lines
sentry_sdk/integrations/starlette.py	100.00%	⚠️ 1 partials

Coverage diff

@@            Coverage Diff             @@
##        master       #PR       +/-##
==========================================
- Coverage    90.17%    89.49%    -0.68%
==========================================
  Files          193       180       -13
  Lines        25768     21514     -4254
  Branches      9532      7814     -1718
==========================================
+ Hits         23236     19253     -3983
- Misses        2532      2261      -271
- Partials      1432      1223      -209

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