[Python] Fail bundles on state write errors

[bvolpato]

Python runtime state commits ignore StateResponse.error, so a runner-reported write failure can still complete the bundle successfully. When an append follows a clear, the clear future is overwritten and its response is never checked.

This change checks pending write responses before completing bag, set, and ordered-list state commits, and retains both futures when an append follows a clear. Write errors fail the bundle through the existing failure handling; successful commits send the same state requests.

Local worker validation passed, and the regressions fail against the unfixed implementation. Run the Python unit suite with:

./gradlew :sdks:python:test-suites:tox:py312:testPython312

When cross-bundle user-state caching is enabled, a retry needs a runner-supplied cache token that prevents reuse of state cached by the failed bundle.

---

• If this contribution is large, please file an Apache Individual Contributor License Agreement.
• Replace these instructions with a description of your change and why you have made it.
• Mention the appropriate issue in your description (for example: addresses #123 or fixes #456).
• Update CHANGES.md with noteworthy changes.

See CONTRIBUTING.md for contribution guidelines.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.74%. Comparing base (76f6e6d) to head (70f308b).
⚠️ Report is 143 commits behind head on master.

Additional details and impacted files

@@              Coverage Diff              @@
##             master   #39992       +/-   ##
=============================================
+ Coverage     56.16%   79.74%   +23.57%     
=============================================
  Files          1124      487      -637     
  Lines        178336    82280    -96056     
  Branches       1489        0     -1489     
=============================================
- Hits         100170    65613    -34557     
+ Misses        75645    16667    -58978     
+ Partials       2521        0     -2521     

Flag	Coverage Δ
go	?
java	?
python	79.74% <100.00%> (+0.18%)	⬆️

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