fix(aws-lambda): fix flake in aws lambda tests

[pabloDeputter]

Description

• Catch subprocess.TimeoutExpired during SAM teardown and force-kill, so slow shutdown cannot fail the entire test suite.
• Added temporary flake-check workflow that runs each test aws-lambda test 5 times to verify this removes the flake (workflow is removed in the last commit; was just to verify that it works). [https://github.com/getsentry/sentry-python/actions/runs/30539137588/job/90862136512?pr=6937](last successful run)
• Switched SAM --warm-containers startup from EAGER to LAZY so Docker containers start on first invocation instead of all 21 at SAM startup. Verified locally by running TESTPATH=tests/integrations/aws_lambda/test_aws_lambda.py uv run tox -e py3.8-aws_lambda both for EAGER & LAZY 10x independently:

EAGER:
=================================================
Metric              |   Mean (s) |  Std Dev (s)
=================================================
Setup time          |      43.69 |         3.99
First call time     |       1.92 |         0.22
Max Teardown time   |       7.49 |         0.27
Total run time      |     108.53 |         4.56
=================================================
LAZY:
=================================================
Metric              |   Mean (s) |  Std Dev (s)
=================================================
Setup time          |      33.32 |         1.82
First call time     |       6.32 |         0.63
Max Teardown time   |       6.90 |         0.18
Total run time      |     102.06 |         3.60
=================================================

Issues

Resolves: #6911 & PY-2632

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 📊

✅ 99295 passed | ⏭️ 6781 skipped | Total: 106076 | Pass Rate: 93.61% | Execution Time: 351m 12s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📈 +420
Passed Tests	📈 +417
Failed Tests	📉 -1
Skipped Tests	📈 +4

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2498 uncovered lines.
✅ Project coverage is 89.87%. Comparing base (base) to head (head).

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
+ Coverage    89.87%    89.87%        —%
==========================================
  Files          193       193         —
  Lines        24656     24656         —
  Branches      8786      8786         —
==========================================
+ Hits         22158     22158         —
- Misses        2498      2498         —
- Partials      1400      1400         —

---

Generated by Codecov Action

[alexander-alderman-webb]

🚀

[sentrivana]

🚀