Fixed the clear all animation on the locked shade

The notifications were also performing a removal animation
even though they were swiped out, which is not needed at all.
Also notifications that were clipped off on the top performed
an animation even though they shouldn't have.

Test: manual, on the shade locked clear all, observe smooth animations
Change-Id: I26c99a1fb48ea7b22e3710a744702af70db32b42
Fixes: 36590278