Fix missing HUN Outro animations

The disappear animation was broken, because we were setting some wrong
values on the HUN animating away:
 - a bottom clipping, which made it to immediately disappear at the start of the animation
 - an yTranslation, which made it to jump around on split shade
 - a wrong height, which made it to flicker during the animation (note: the height flickering only happened if there were other HUNs moving into the shade in the meantime -> the avalanche is the typical use case)

Fixes: b/282624825
Test: atest StackScrollAlgorithmTest
Test: atest create HUNs and observe the animations

Change-Id: If0c1e4f439a3011b5ea499edc2128aa417279ec8