BUG: Update Styler.clear method to clear all
- [ x ] closes #40484 
- [ x ] tests added / passed
- [ x ] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [ x ] whatsnew entry updated in docs

Thank you for the review guys! I'll make the change above.

Curious fails in the CI tests yesterday though - was going through some of the logs last night; the errors arose from modules/code lines I didn't touch (pulled from repo :S) thanks @bsun94  thank you guys for the review!