Remove starting destination bounds on BOUNDS PIP Shell Transition.

We don't need to set any starting bounds on non-alpha animations.
Also fixed a potential possibility where swipeToHome gets reset too
early by PipTaskOrganizer, and moved it to PipTransition instead.

Bug: 165793917
Bug: 193565745
Test: atest EnterPipTest
Change-Id: Icd579b1165a62cb61a6c1eed0d659d788c16608c