BUG+DEPR: undeprecate item, fix dt64/td64 output type
- [x] closes #29250
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Does the un-deprecation need a dedicated discussion, or is there consensus on that?

I'd be happy to split this into separate bug/depr pieces of reviewers prefer.