[Bug] Removing handlers in Background Logger extension removes only one handler.

[kuchara]

Describe the bug
setup_server_logging() @ extensions/logging/logger.py (https://github.com/sanic-org/sanic-ext/blob/main/sanic_ext/extensions/logging/logger.py#L49) mutates logger_instance.handlers list while iterating over it. This is not correct.

for handler in logger_instance.handlers:
      logger_instance.removeHandler(handler)

If there are 2 handlers, most often, only one of them is being removed.

To Reproduce
N/A

Expected behavior
Mentioned code should remove all handlers, and replace them by a QueueHandler instance.

Environment (please complete the following information):

• OS: Ubuntu 22.04.3 LTS @ WSL2
• Browser: N/A
• Version: N/A

Additional context
My proposal to fix would be something like described in https://stackoverflow.com/questions/7484454/removing-handlers-from-pythons-logging-loggers :

for handler in list(logger_instance.handlers):
    logger_instance.removeHandler(handler)

Note: none of the options from the linked SO question is thread safe, but Python so far does not provide method to safely cleanup all handlers in one instruction.

See also on mutating list while iterating: https://discuss.python.org/t/how-safe-documented-is-it-to-mutate-a-list-being-iterated/18929