DEPR: Hide deprecated attrs _AXIS_NAMES & _AXIS_NUMBERS
- [x] closes #38722
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Users that do e.g. `[getattr(pd.DataFrame, x) for x in dir(pd.DataFrame())]` or `inspect.getmembers(pd.DataFrame())` currently get an unfriendly deprecation warning. This fixes that by adding `_AXIS_NAMES` & `_AXIS_NUMBERS` to `_hidden_attrs`.

@JSunRae, is it possible for you to add this to your pandas source code and see if this fixes your problem?

xref: #33637