CLN: Clean DirNameMixin._deprecated
This moves the content of ``DirNameMixin._deprecations`` to more appropriate locations, typically ``IndexOpsMixIn._deprecations``, as that is a common subclass of ``Index`` and ``Series``. The names in ``DirNameMixin._deprecations`` belonged to those two classes, so having the deprecated names located all the way up in ``DirNameMixin`` made them be available in all classes that subclass ``DirNameMixin``, which was unfortunate.

By having ``DirNameMixin._deprecations`` start with an empty set, it will be easier to use
``DirNameMixin`` and ``PandasObject`` where/when needed, without inheriting undesired names in ``_deprecated``.

This PR also moves ``"tolist"`` to ``IndexOpsMixIn._deprecations``, because ``tolist`` is defined in that class.

Thanks @topper-123 