Handle auto-pip change in split handling transitions

An auto-pip change might get collected into the transition which has
already claimed by split handler. This makes sure to handle the mixed
transition between split handler and pip handler.

Fix: 285816139
Test: open a fullscreen app on top of a split pair with auto-pip app.
      verified expanding the pip window, split pair is dismissed in
      overview.
Change-Id: I5c723000e7ddc6a96b8992960845400c152ed3d2