opentelemetry-instrumentation-pika: avoid duplicate consumer wrapping

[popsiclelmlm]

Description

Fixes #4667.

Summary

Avoid wrapping an already-instrumented pika consumer callback again when _instrument_channel_consumers runs more than once for the same channel.

Reproduction

A BlockingChannel can call basic_consume multiple times. The instrumentation reruns _instrument_channel_consumers after each registration. The new regression test calls _instrument_channel_consumers twice for the same channel and asserts the callback remains the first decorated function.

Root cause

_instrument_channel_consumers decorated every callback in the channel consumer map each time it ran. Previously registered callbacks could therefore accumulate nested consumer span wrappers.

Changes

• Skip callbacks that already carry _original_callback metadata.
• Add a regression test for repeated consumer instrumentation on the same BlockingChannel.
• Add a changelog fragment.

Tests

• .venv-tox/bin/tox -e py314-test-instrumentation-sio-pika-1-wrapt2
• .venv-tox/bin/tox -e py314-test-instrumentation-sio-pika-0-wrapt2
• .venv-tox/bin/tox -e lint-instrumentation-sio-pika
• .tox/lint-instrumentation-sio-pika/bin/ruff check instrumentation/opentelemetry-instrumentation-pika/src/opentelemetry/instrumentation/pika/pika_instrumentor.py instrumentation/opentelemetry-instrumentation-pika/tests/test_pika_instrumentation.py
• .tox/lint-instrumentation-sio-pika/bin/ruff format --check instrumentation/opentelemetry-instrumentation-pika/src/opentelemetry/instrumentation/pika/pika_instrumentor.py instrumentation/opentelemetry-instrumentation-pika/tests/test_pika_instrumentation.py
• git diff --check

Screenshots/Logs

N/A. This is a unit-level instrumentation fix.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Does This PR Require a Core Repo Change?

• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[herin049]

Looks good to me, just a few small comments.

[herin049]

Why not just?

Suggested change

	if "_original_callback" in getattr(
	consumer_callback, "__dict__", {}
	):
	if hasattr(consumer_callback, "_original_callback"):

[herin049]

It also might be worth adding a warning log here.