[PB] Do not create windowless splash screen surface...

if previous activities haven't stopped. So the previous activities
can play animation right after previous transition finish.
Also release the windowless surface in core side if the animation
was already finished.

Flag: EXEMPT bugfix
Bug: 351061106
Test: disable snapshot, trigger back gesture right after an open
activity transition, verify no windowless surface created.

Change-Id: I65c9ece1a095877e45340f6516c76850b5254812