Fix not clearing split pair record after auto-enter pip

Due to the swipe-to-home and entering pip are in separate transitions.
The split record was not removed after startAnimation, updates to remove
it when identified in handleRequest.

Bug: 273410079
Test: repro steps of the bug
Change-Id: Iad54a3d87c1d926e4148c937712e45fdc44d6e82