Notify unlock controller when remote animation ends due to null finishedCallback.

In some cases, when unlocking to an activity that is
rotating, we can end up getting a null apps/callback
since the activity we were unlocking to is destroyed.

In this case, we should still tell the unlock
controller that the animation has ended, so that we
can reset state. This was resulting in the launcher
icons being 'prepared' for unlock indefinitely,
leaving them invisible/shrunken.

Fixes: 231690494
Test: rotate to landscape, lock, keep phone physically in landscape, unlock to launcher
Change-Id: I1e019fabc988f9ad316824d29e3d6fda5f62177b