Fix logging instrumentation

[selcukcihan]

Description

• Related issue https://linear.app/serverless/issue/SC-1249/loggingwarning-cannot-handle-passing-an-exception
• Mimic the logic of Logger.error & Logger.warning in terms of the interpretation of the arguments. The crucial part that was not working is stringifying the first argument and using it as a formatter: https://github.com/python/cpython/blob/main/Lib/logging/__init__.py#L387
• Handle exceptions in the warning method as we do in error, passing it as is without stringifying it because it will get stringified in a different way within the create_warning_captured_event method.

Testing done

Reproduced customer's exact issue and more in a unit test

[selcukcihan]

@medikoo @Mmarzex ready for review 🙏