Only switch item animator on content fill if needed

We currently switch to a different recycler view item animator for a
special content fill animation when we have loading item UI up and want
to animate to the actual content. However, it's possible if the task
content loading is fast enough, we may return before the adapter
changes have actually propogated to the recycler view layout. In this
case there is no loading UI to fill and we should not switch item
animators.

Bug: 130820737
Test: Go from app => overview, try to remove, remove animation occurs
properly
Change-Id: Ic95854d04df98023f444daf967c58bdd8177722a
(cherry picked from commit 035f0d21)