fix(unit_test): prevent logging from raising exceptions after tests

[tchaikov]

pytest's capsys just closes the stdout when done with tests. there are issues tracking this problem, see pytest-dev/pytest#5577 . but we adds a handler which redirect the logging messages to stdout. so, once pytest finishes testing, exceptions are raised when writing logging messages, like

22:37:20    File "/usr/local/lib/python3.10/logging/__init__.py", line 1101, in emit
22:37:20      stream.write(msg + self.terminator)
22:37:20  ValueError: I/O operation on closed file.

so, in this change, logging.raiseExceptions is disabled when pytest's session finishes.

Fixes #6000

PR pre-checks (self review)

• I followed KISS principle and best practices
• I didn't leave commented-out/debugging code
• I added the relevant backport labels
• New configuration option are added and documented (in sdcm/sct_config.py)
• I have added tests to cover my changes (Infrastructure only - under unit-test/ folder)
• All new and existing unit tests passed (CI)
• I have updated the Readme/doc folder accordingly (if needed)

[fruch]

LGTM,

still we have a few PytestUnhandledThreadExceptionWarning being raised during the tests
but that's by very specific test that doesn't check their background threads for some reason.

[vponomaryov]

LGTM