CLN: prelims for MultiIndex.get_value
Unravelling MultiIndex.get_value and get_loc is shaping up to be a PITA.  This separates out the easiest parts of the get_value cleanup.

@TomAugspurger can you confirm that the change made here to the `__finalize__` call is correct?  If so, suggest a test?

needs a rebase, and now that I think about it, try_mi really should NOT be where it is, it actually should be a series method i think. > try_mi really should NOT be where it is

I'm hoping we can get it into `_get_values_for_loc`, separate PR Closing in favor of #31736.