Animating when the qs boundary changes due to notification interactions

When dismissing notifications, the logic how the scrolling was adapted
wasn't updated yet, leading to accidental scrolls after dismisses.
Additionally, we're now animating these changes properly when the
boundary changes for these events.

Fixes: 188439802
Test: have a couple of notifications, scroll, dismiss the first notification, observe nice animation
Change-Id: Ic4faec910a7ca82fd283ab2053ddb4222668a161