BUG: DataFrame.drop unexpectedly drops frequency
- [x] closes #58743 
- [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/v3.0.0.rst` file if fixing a bug or adding a new feature.

im not convinced this is something we should do.  this seems like a case where users shouldn't be using `drop` in the first place I'm not convinced, either. In any case, I don't think it's desirable for `drop` to implicitly set `freq` to `None`. If `DatetimeIndex` has a `freq`, it should be retained, and if it is explicitly `None`, it should remain `None`.

Thank you so much again for your review. Yeah I'm not convinced this complexity is worth adding. Thanks for the PR but going to close for now