Performance of maybe_box_datetimelike #30520
- [x] closes #30520
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] `maybe_box_datetimelike` avoids unnecessary conversion of `value` to `tslibs.Timestamp` or `tslibs.Timedelta` if `value` is already an instance of `tslibs.Timestamp` or `tslibs.Timedelta`.
