fix: forward http_options in async_request_streamed to enable retry support

[acoroleu-tempus]

Summary

• Fixes RetryHttpOptions ignored for client.aio.models.generate_content_stream #2044 -- client.aio.models.generate_content_stream ignores HttpRetryOptions and performs no retries, while the sync client.models.generate_content_stream retries correctly.
• Root cause: async_request_streamed did not pass http_options to _async_request, so per-request retry options were silently dropped.
• One-line fix: forward the http_options parameter, matching what the sync request_streamed already does.

Test plan

• Added 12 new streaming retry tests to test_retries.py covering:
  • Sync httpx streaming (4 tests, baseline reference)
  • Async httpx streaming (4 tests)
  • Async aiohttp streaming (4 tests)
  • Each backend tests both client-level and request-level retry options, for both successful and unsuccessful retry scenarios
• Verified all 12 new tests fail before the fix and pass after
• Verified all 38 tests in test_retries.py pass (26 existing + 12 new)

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[Venkaiahbabuneelam]

Hi @acoroleu-tempus , Thanks for reaching out us!

Looks like branch is out of date, Kindly please update the branch.

Thanks

[acoroleu-tempus]

@Venkaiahbabuneelam done