fix(litellm): set ERROR status on streaming spans that fail mid-stream

[chiliec]

Fixes #4013.

What

The sync (_finalize_sync_streaming_span) and async (_finalize_streaming_span) chat-completion streaming finalizers only called span.record_exception(e) when a stream failed mid-way (connection dropped, MidStreamFallbackError, etc.), leaving the span status UNSET. The non-streaming wrappers already set StatusCode.ERROR, so failed streaming calls were invisible to error views and alerts that filter on span status.

This adds span.set_status(Status(StatusCode.ERROR, str(e))) next to the existing record_exception in both finalizers — matching the non-streaming behavior.

Tests

Added two tests to tests/test_instrumentor.py (test_completion_sync_streaming_sets_error_status_on_mid_stream_failure, test_acompletion_streaming_sets_error_status_on_mid_stream_failure) that drive a stream raising mid-iteration and assert the span ends with StatusCode.ERROR plus one exception event.

Validation

$ python -m pytest tests/test_instrumentor.py \
    -k "test_completion_sync_streaming_sets_error_status_on_mid_stream_failure or test_acompletion_streaming_sets_error_status_on_mid_stream_failure"
2 passed

RED→GREEN confirmed: before the source change both tests fail with assert <StatusCode.UNSET> == <StatusCode.ERROR>; after it, both pass.

Broader streaming/exception/status selection (-k "stream or exception or status"): 22 passed. One unrelated test (test_completion_streaming_with_extended_thinking_anthropic) fails on this machine because its VCR cassette tries to reach a live Anthropic endpoint — it fails identically on the unmodified main, so it is not caused by this change.

[github-actions]

CLA Assistant Lite bot:
Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

---

I have read the CLA Document and I hereby sign the CLA

---

_{You can retrigger this bot by commenting recheck in this Pull Request}