{Log} Adapt az_command_data_logger to Knack 0.8.0

[jiasli]

Adapt to microsoft/knack#228: [Log] CLILogging.configure returns as early as possible

Symptom

az feedback no longer works with knack dev branch:

> azdev test feedback

src\azure-cli\azure\cli\command_modules\feedback\tests\latest\test_feedback.py:130: in _helper_test_log_contents_correct
    self.assertEqual(command_log_files[1].get_command_status(), "SUCCESS")
E   AssertionError: '' != 'SUCCESS'
E   + SUCCESS

Cause

In pytest environment, pytest will configure the root logger to capture all logs.

• The old knack always forcibly set root logger level to DEBUG.

• The new knack can detect that and it leaves pytest root logger as is ([Log] CLILogging.configure returns as early as possible microsoft/knack#228).

  In such case, we have to manually set az_command_data_logger's level to DEBUG, otherwise it will honor pytest root logger's level and be WARNING by default (when --log-level is not set). This makes az_command_data_logger's log be ignored. For more info on how Python logging works, see logging.Logger.getEffectiveLevel.

Additional Context

• az feedback relies on az_command_data_logger (which are written to ~/.azure/commands/).

• az_command_data_logger is written by azure.cli.core.util.handle_exception.

• During testing, azure.cli.core.util.handle_exception is mocked by azure.cli.testsdk.patches.patch_main_exception_handler so that the original Exception can be thrown and asserted.

• However, azure.cli.testsdk.patches.patch_main_exception_handler doesn't write to az_command_data_logger.

• In the oldest code ([wip] az feedback #8829), this is worked around by calling the leaked file handler after execute finishes.

• As [Core] fix logging file fd leaking #13102 fixed the leaked file handler, the old code no longer worked. To work around it again, [Core] fix logging file fd leaking #13102 manually delayed the cleanup for file handler.

• This PR refactors [Core] fix logging file fd leaking #13102 with a more elegant mock.patch on azure.cli.core.util.handle_exception again, so that no manual delay of file handler cleanup is necessary.

[jiasli]

The old code registers Logger as a Handler. It works simply because both Logger and Handler expose handle method by coincidence. It is never guaranteed to work as such and may break any time the internal logic of logging module changes.

[jiasli]

CommandLoggerContext will be called again at:

azure-cli/src/azure-cli-core/azure/cli/core/azclierror.py

Lines 62 to 65 in 4560e96

	def print_error(self):
	from azure.cli.core.azlogging import CommandLoggerContext
	from azure.cli.core.style import print_styled_text
	with CommandLoggerContext(logger):

Calling it here is redundant.

Besides, no log is written here, so these lines shouldn't be surrounded by CommandLoggerContext.

[jiasli]

No log is written here. The scope of CommandLoggerContext should be as small as possible.

[yonzhan]

Log