core[patch]: Update `AsyncCallbackManager` to honor `run_inline` attribute and prevent context loss (#26885)
## Description
This PR fixes the context loss issue in `AsyncCallbackManager`,
specifically in `on_llm_start` and `on_chat_model_start` methods. It
properly honors the `run_inline` attribute of callback handlers,
preventing race conditions and ordering issues.
Key changes:
1. Separate handlers into inline and non-inline groups.
2. Execute inline handlers sequentially for each prompt.
3. Execute non-inline handlers concurrently across all prompts.
4. Preserve context for stateful handlers.
5. Maintain performance benefits for non-inline handlers.
**These changes are implemented in `AsyncCallbackManager` rather than
`ahandle_event` because the issue occurs at the prompt and message_list
levels, not within individual events.**
## Testing
- Test case implemented in #26857 now passes, verifying execution order
for inline handlers.
## Related Issues
- Fixes issue discussed in #23909
## Dependencies
No new dependencies are required.
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@eyurtsev: This PR implements the discussed changes to respect
`run_inline` in `AsyncCallbackManager`. Please review and advise on any
needed changes.
Twitter handle: @parambharat
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Co-authored-by: Eugene Yurtsev <eyurtsev@gmail.com>