Make sure to release split layout when returning to home

When returning to home from recent apps, the splitting tasks were
already hidden while performing the recent transition, so dismiss split
screen directly without requesting dismiss transition. Also reorder to
make sure it collects all clean-up operations before finishing the
transition.

Fix: 226682648
Bug: 206487881
Test: verify with the repro steps of the bug
Change-Id: I05e7ae6fa26631203d652ccb532fb57f532794d7