Fixed an issue where the clipping would be wrong when collapsing

When collapsing the shade, our clipping logic was wrongly assuming
that the full actualHeight lead to the visible background bottom
which is not accurate. For groups, we also set the clipBottomAmount
that impacts its position and that should be taken into account
when clipping, otherwise it would lead to holes.

Fixes: 422119449
Tests: atest SystemUITests
Flag: com.android.systemui.physical_notification_movement
Change-Id: Ibfad00f99518b80316ace4fc00bb958ab426321c