[Bug]: Colorbar format string kind guess could be made more robust #27007

Bug summary

When the format kwarg passed to colorbar() is a str, colorbar() currently tries to guess whether it is a %-format or a {}-format string, using

        if isinstance(format, str):
            # Check format between FormatStrFormatter and StrMethodFormatter
            try:
                self._formatter = ticker.FormatStrFormatter(format)
                _ = self._formatter(0)
            except TypeError:
                self._formatter = ticker.StrMethodFormatter(format)

Even ignoring the (contrieved) case where the format string is valid both as a %-format and a {}-format, there are other failure cases which could be easily handled, specifically format="{x}%" ("I want to format the value with a percent-sign appended to it"): here the _formatter(0) call will fail with a ValueError (which just needs to be caught) rather than a TypeError.

Code for reproduction

# see above

Actual outcome

ValueError raised.

Expected outcome

Format string used as expected.

Additional information

Probably just needs additionally catching ValueError, plus a test.

Operating system

No response

Matplotlib Version

3.8

Matplotlib Backend

No response

Python version

No response

Jupyter version

No response

Installation

from source (.tar.gz)