BUG: is_categorical shouldnt recognize Dtype objects
is_categorical(obj) is used in a couple places where we then go on to access `obj.dtype`, so this should not return `True` if we have a `CategoricalDtype` object.
This will need a deprecation cycle right? > This will need a deprecation cycle right?

id classify this as a bugfix, but OK either way the other option is just to deprecate it, since we only use is_categorical in a few places and its more likely than not to cause confusion Closing in favor of #33385.