fix: early OpenTelemetry context propagation in invocation

[hallvictoria]

Description

Fixes #1626

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Move OpenTelemetry context propagation earlier in _handle__invocation_request to ensure all logs have proper trace context (Operation Id) in Application Insights.

Problem: When OpenTelemetry is enabled, the first log emitted in _handle__invocation_request had a blank Operation Id because configure_opentelemetry() was called after the first log was emitted.

Solution: Move fi_context initialization and configure_opentelemetry() call to immediately after FunctionInfo is retrieved, before any logging occurs.

Pull Request Checklist

Host-Worker Contract

• Does this PR impact the host-worker contract (e.g., gRPC messages, shared interfaces)?
  • If yes, have the changes been applied to:
    • azure_functions_worker (Python <= 3.12)
    • proxy_worker (Python >= 3.13)
  • If no, please explain why: This PR only changes the order of operations within the invocation request handler. No gRPC messages or shared interfaces are modified.

Worker Execution Logic

• Does this PR affect worker execution logic (e.g., function invocation, bindings, lifecycle)?
  If yes, please answer the following:

Python Version Coverage

• Does this change apply to both Python <=3.12 and 3.13+?
• If yes, have the changes been made to:
  • azure_functions_worker (Python <= 3.12)
  • runtimes/v1 / runtimes/v2 (Python >= 3.13)
• If no, please explain why:

Programming Model Compatibility (for Python 3.13+)

• Does this change apply to both:
  • V1 programming model (runtimes/v1)?
  • V2 programming model (runtimes/v2)?
• Explanation (if limited to one model): Change applies to both models as both have the same late context propagation issue.

[Copilot]

Pull request overview

This PR addresses late OpenTelemetry context propagation during function invocation handling so that invocation logs are correlated with the proper trace context (Operation Id) in Application Insights.

Changes:

• Move OpenTelemetry context initialization/configuration earlier in the invocation request handlers (worker dispatcher + v1/v2 runtimes).
• Remove the later (async-only) OpenTelemetry configuration points after args/bindings setup.
• Add a unit test intended to validate that OpenTelemetry is configured before the first invocation log in the worker dispatcher.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 8 comments.

File	Description
workers/tests/unittests/test_opentelemetry.py	Adds tests to validate OpenTelemetry context propagation occurs before the first invocation log.
workers/azure_functions_worker/dispatcher.py	Moves _get_context + configure_opentelemetry() before the first logger.info in _handle__invocation_request.
runtimes/v2/azure_functions_runtime/handle_event.py	Moves context creation + OpenTelemetry configuration before the first invocation logger.info.
runtimes/v1/azure_functions_runtime_v1/handle_event.py	Moves context creation + OpenTelemetry configuration before the first invocation logger.info.

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