Removing slots in the Iterate() method performs an atomic CAS operation
on a cell. This is not necessary, we can simply keep slots and drop
the whole SlotSet with all buckets after iteration.

Bug: v8:12760
Change-Id: I6aeb656d21e5fea6f7e15238d4105013c84ffb2a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3574558Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79863}