Remove bouncer root view whenever it is not needed.

1. Finishing a transition from * -> Gone removes the bouncer parent view
2. Starting a transition from Gone -> * adds the bouncer parent view

Removing the bouncer parent view cancels all the coroutines launched by the compose bouncer

Fixes: 364401028
Test: verified that compose bouncer works as expected, added logs to verify that bouncer is removed and re-added
Flag: com.android.systemui.compose_bouncer
Change-Id: I167a55284b13940d331c96f4a72defe2cc069aba