The StackScrollAlgorithm was modified such that the notifications
now don't layout anymore during scrolling and therefore
intermediate states are avoided except for the first card.
Also made the top stack a bit smaller and fixed a bug where the
scrolling was not working on the very first try.
Bug: 14080821
Bug: 14081652
Change-Id: I924a9f8532486856fc2ecd88f6c10d26023a5bc3