Clear the swipe PiP on legacy enter path

We hit the case that auto-enter-pip is trigged in Launcher and no actual
PiP transition is made. Which leads to a broken internal state and
blocks exit PiP if a legacy-enter-pip is made after.

Fixing this by clear the state on the legacy enter path.

Flag: EXEMPT bugfix
Bug: 365300020
Test: N/A added as a fail safe based on analyze
Change-Id: I004f0654f0287f006422d43ebd44d92ec009c1fc