Polish home-key from split to pip transition

Includes WINDOWING_MODE_MULTI_WINDOW closing target to the condition of
playing fallback animation. So the remaining splitting task won't be
play with iconview animation when home-key to auto-pip consumed another
splitting task in pip transition handler.

Bug: 281476331
Test: repro steps of the bug
Test: pass existing tests
Video: http://recall/-/fLARJNt42LVxc3tt86SneW/eelqATeE1REoOtOEDxeDVR
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:365105118220b218005225b038142273524877cc)
Merged-In: If05d8841a6a940e61f71683422ef1a3d4e3597c7
Change-Id: If05d8841a6a940e61f71683422ef1a3d4e3597c7