[iOS] inactiveTabsCoordinator owns the ActionSheetCoordinator.

Up to now, the action sheet coordinator was directly deallocated. It
had no side effect, since it was not used anymore. It also means it
could not be properly stopped.

Fixed: 1465783
Change-Id: Ifbc193cb75dad4fabd16673dd48ae2ba37ea8a11
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4691503
Commit-Queue: Arthur Milchior <arthurmilchior@chromium.org>
Reviewed-by: Louis Romero <lpromero@google.com>
Cr-Commit-Position: refs/heads/main@{#1171675}