REGR/DOC: pd.concat should special case DatetimeIndex to sort even when sort=False
- [x] closes #57006
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [x] Added an entry in the latest `doc/source/whatsnew/v2.2.1.rst` file if fixing a bug or adding a new feature.

Reverts the changes from #54769 due to long-standing behavior and documents the behavior instead.

See discussion regarding the inconsistency of the long-standing behavior here: https://github.com/pandas-dev/pandas/issues/57006#issuecomment-1913562404
thx @lukemanley  IMO I think this case should still be deprecated. Carve-outs like this ultimately lead to confusion > IMO I think this case should still be deprecated. Carve-outs like this ultimately lead to confusion

I opened https://github.com/pandas-dev/pandas/issues/57335 for discussion.