Simplify the log._Formatter

[LecrisUT]

For reference the original code for Python3.9 that we still support is:
https://github.com/python/cpython/blob/0bbaf5de9744ae1acea3e2c9ad2257d1cc68e847/Lib/logging/__init__.py#L650-L680

        record.message = record.getMessage()
        if self.usesTime():
            record.asctime = self.formatTime(record, self.datefmt)
        s = self.formatMessage(record)
        if record.exc_info:
            # Cache the traceback text to avoid converting it multiple times
            # (it's constant anyway)
            if not record.exc_text:
                record.exc_text = self.formatException(record.exc_info)
        if record.exc_text:
            if s[-1:] != "\n":
                s = s + "\n"
            s = s + record.exc_text
        if record.stack_info:
            if s[-1:] != "\n":
                s = s + "\n"
            s = s + self.formatStack(record.stack_info)
        return s

other than the check for record.message (which effectively makes no difference if it is re-rendered with record.getMessage()) I do not see any other functional change here.

Pull Request Checklist

• implement the feature

[gemini-code-assist]

Code Review

This pull request simplifies the custom log formatter _Formatter by removing a reimplementation of logging.Formatter.format. The new implementation overrides formatMessage to apply decolorization, and relies on the superclass's format method for the main formatting logic. This change reduces code duplication. A compatibility shim for typing.override has been added to support older Python versions. The changes are correct.

[thrix]

Clean simplification. The old format() duplicated CPython's Formatter.format() logic; the new formatMessage() override applies decolorization at the right point while inheriting all the standard exc_info/stack_info handling. The hasattr(record, 'message') check was effectively a no-op since getMessage() sets it anyway. Nice -35 lines.

[LecrisUT]

Marked as blocked by #4676 (the first commit in the series), otherwise should still be fine for review