[Feature][OTel]: Move on invocation start and end to worker thread

[wangyb-A]

What would you like?

• Move on invocation start and end to worker thread, instead of main thread.
• Attach and de-attach to otel context

Possible Implementation

No response

Is this a breaking change?

No

Does this require an RFC?

No

Additional Context

No response

[AdityaAudi]

@wangyb-A I took a look and wanted to sanity-check intent before picking this up, since the design has a couple of forks:

1. Should all plugin callbacks move to the worker thread, or just invocation start/end? Moving only the two creates an ordering
   hazard, operation callbacks (still sync) could fire on the user-code thread before the invocation span exists.
2. My lean is to capture the Context snapshot in on_invocation_start and pass it explicitly into downstream start_span(context=...) calls, rather than relying on context.attach() (per-thread via contextvars, so it doesn't cross the worker→user-code boundary cleanly). Open to a different model if you had one in mind.
3. Assuming this means the missing context.detach() at the end of on_user_function_end (there's an existing comment skipping it at plugin.py) or did you mean something broader?

Happy to start on a PR once these are settled.