gh-132285: Fix that __annotate__ is not deleted when __annotations__ is deleted

[sobolevn]

• Issue: __annotate__ corner case when deleting __annotations__ #132285

[JelleZijlstra]

I think this actually behaves incorrectly. In https://peps.python.org/pep-0749/#effect-of-deleting-annotations we said that deleting __annotations__ should also delete __annotate__. type_set_annotations() tries to do that but it's buggy; do you want to fix it?

[sobolevn]

Yes, sure :)
Checking type_set_annotations