Remove BubbleTaskViewTransitions

This is a cleanup that the BubbleTaskViewTransitions is no longer
needed because the Bubble transitions are now handled by the
default mixed handler

Sets the trampoline Task to be always-on-top when the bubble Task
is created instead.

Bug: 388651207
Test: launch Calendar to bubble
Flag: com.android.wm.shell.enable_create_any_bubble
Change-Id: I089f5ca53597a6d7ae160e23b32cfaa47652c637