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.
This issue is https://github.com/pandas-dev/pandas/issues/29250 also needs a rebase LGTM, assuming that https://github.com/pandas-dev/pandas/pull/30175/files/0d2867d5518ac8e5032e7dfca5d0adb5811fa84d#diff-9c718a39eb63c1bfac4fbeacf2906ffd 
has been addressed. Thanks @jbrockmendel !

(will look into adding a EA test)