Introduce StdoutCaptureManager to isolate stdout from logging logs

[Dev-iL]

As part of adding some debug logging in another PR, a lot of tests failed because they appear to capture all the logs then compare them (for equality) to some expected output.

The initial plan was to use caplog to isolate the logger of interest, then use membership/intersection for assertions instead of equality. However, upon closer inspection of the failures, it quickly became apparent that their majority was related to CLI tests, which assert against stdout and not some particular logger. So a different approach was taken, which is to create a context manager fixture that filters out messages originating from the logging module.

In addition, some uses of unittest.mock were replaced with pytest's mocker fixture.

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[Copilot]

Pull Request Overview

This PR introduces a StdoutCaptureManager context manager to isolate stdout capture from logging output in CLI tests, preventing test failures caused by debug logging interference. The context manager filters out log messages that would otherwise contaminate stdout assertions in CLI command tests.

• Adds a new StdoutCaptureManager class that removes stdout logging handlers during stdout capture
• Replaces unittest.mock usage with pytest's mocker fixture across multiple test files
• Updates CLI test files to use the new stdout_capture fixture instead of direct redirect_stdout calls

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

File	Description
airflow-core/tests/unit/cli/conftest.py	Adds the StdoutCaptureManager class and stdout_capture pytest fixture
airflow-core/tests/unit/cli/commands/test_*.py	Updates CLI command tests to use new stdout capture fixture and pytest mocker

[potiuk]

Let's hope there will be no more flakiness :)