Fix bubble bar bounce animation issue

The bubble bar bounce animation was assuming that the initial translation
of the bubble bar is also the translation the bubble bar should have at
the end of the animation. This is normally correct except when the
bubble bar is initially hidden. What happens in that case is that the
translation is 0 so the bubble bar gets animated incorrectly.

This change gets the target animation from stash controller.

ABTD 100 runs: https://android-build.corp.google.com/abtd/run/L26900030004638356/

Flag: com.android.wm.shell.enable_bubble_bar
Fixes: 347856510
Test: atest BubbleBarTest#selectDifferentBubble
Change-Id: I661bf006c6f23ff871c221f8d9da74d79a2dff11