BUG: Series.getitem not falling back to positional for bool index

[phofl]

• [x] closes #48653 (Replace xxxx with the Github issue number)
• [x] Tests added and passed if fixing a bug or adding a new feature
• [x] All code checks passed.
• [x] Added type annotations to new arguments/methods/functions.
• [x] Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

cc @jbrockmendel