[iOS] Avoid calling delegate if the button is disabled

There is a tiny timing when a button is disabled from our side and when
it is disabled from Apple API side. To avoir calling button when we
explicitly disabled it, check before the state of the button before
calling the delegate.

Bug: 1457146, 1501688
Change-Id: I8ca8c52d39bc155bc4d43ad744828f715ae23c14
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5024522
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Commit-Queue: Aliona Dangla <alionadangla@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1224183}