Fix IllegalStateException in TabGridItemTouchHelperCallback#clearView

Some weird logic was added to TabGridItemTouchHelperCallback#clearView
to prevent dragged views from getting stuck in the RecyclerView if a
clearView event occurred. Lately this started throwing
IllegalStateException possibly as a result of
https://chromium-review.googlesource.com/c/chromium/src/+/5657210

To avoid regressing either the original bug or the behavior improvement
from the linked CL. This CL keeps the old logic, but posts to avoid
the IllegalStateException from firing. Use extensive null checks for
defense, and ensure the layout position matches and view holder still
has a parent before proceeding with removal.

Fixed: 361498419
Change-Id: I19b02664498c49b1edd05e4e77324a51a392906f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5823833
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Commit-Queue: Calder Kitagawa <ckitagawa@chromium.org>
Reviewed-by: Sky Malice <skym@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1348613}