fix(openai): propagate asyncio.TimeoutErrors correctly when openai operation canceled [backport 2.10]

[sabrenner]

Backport 16cdd6a from #10265 to 2.10.

Fixes #10191

In the case of an asyncio future cancellation, we want to propagate that error up appropriately. What this looks like is the response from the OpenAI function being None, which does not conform to the typing from the OpenAI SDK (see original issue). If the result is ever None, we don't pass that result to our shared generator to handle OpenAI responses, and instead let the error bubble up.

Checklist

• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
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Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
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• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
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• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: backport-10265-to-2.10
Commit report: d0ac57b
Test service: dd-trace-py

✅ 0 Failed, 1218 Passed, 107 Skipped, 13m 25.99s Total Time

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-08-21 18:16:39

Comparing candidate commit d0ac57b in PR branch backport-10265-to-2.10 with baseline commit 63edc2e in branch 2.10.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 221 metrics, 9 unstable metrics.