BUG: always strip .freq when putting DTI/TDI into Series/DataFrame
ATM when we put a DatetimeArray/TimedeltaArray/DatetimeIndex/TimedeltaIndex (from here on, just "DTI") into a Series or DataFrame, we drop its .freq for BlockManager-DataFrame cases, but not the other three cases (BlockManager-Series, ArrayManager-DataFrame, ArrayManager-Series).

The long-term behavior is definitely going to always drop the freq (more specifically, DTA/TDA won't _have_ freq, xref #31218).  So this PR standardizes always-dropping.

cc @mroeschke this should unblock your window PR

cc @jorisvandenbossche bc this touches ArrayManager
looks fine, can you rebase & add a user facing note. ping on green. ping