API/CLN: simplify CategoricalBlock.replace
- [x] closes #33272 
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Makes DataFrame.replace on Categorical behave like Series.replace.
The follow-up to this lets us get the `filter` kwarg out of `BlockManager.apply`