fix(grpc): auto-instrument gRPC seems breaking Pub/Sub streaming pull of exactly once delivery

I apologize for not having a minimum reproducible test case.
It is unclear to me how auto-instrumentation of gRPC affects Pub/Sub.
Perhaps it has something to do with google.cloud.pubsub_v1.subscriber.message.Message.
So this ticket is just for the record.
Hope experts may shed some light on it.

Describe your environment

(Docker official image python:3.10-slim-bookworm)
OS: slim-bookworm
Python version: 3.10
Package version: 0.48b0

What happened?

https://cloud.google.com/pubsub/docs/exactly-once-delivery#pull_subscription_2
The line below isn't responding (such that the callback isn't working)

streaming_pull_future.result(timeout=timeout)

Steps to Reproduce

• Imitate https://cloud.google.com/pubsub/docs/exactly-once-delivery#pull_subscription_2
• Auto-instrument gRPC
• Send a message to the subscription path

Expected Result

The callback should work

Actual Result

The line below isn't responding (such that the callback isn't working)

streaming_pull_future.result(timeout=timeout)

Additional context

No response

Would you like to implement a fix?

No

Start by reproducing the linked Pub/Sub exactly-once delivery example in Python 3.10 with gRPC auto-instrumentation enabled. Investigate why streaming_pull_future.result(timeout=timeout) does not return and whether the callback is invoked; the work is done when the callback responds after a message is sent.