Improve empty choices handling in streaming chunks

[PeterDaveHello]

GitHub Copilot summary:

This pull request improves the robustness of the streaming reply handler in app/openai_ops.py by updating how chunks without choices are handled. Instead of only checking for Azure-specific empty chunks, the code now gracefully skips any chunk missing choices, logging a debug message for easier troubleshooting.

Streaming robustness improvements:

• Updated the chunk handling logic in consume_openai_stream_to_write_reply to skip and log any stream chunk that is missing choices, not just those from Azure, improving compatibility and debuggability.

[seratch]

Thanks!