Remove remaining cases where we cancel back to the app

- Until we have better infra we can't currently return to the app when
  canceling a recents transition as it can cause a deadlock blocking
  the processing of subsequent transitions.  In these cases though we
  are just merging a transtion that has already updated the WM hierarhcy
  so canceling to home is probably fine.

Fixes: 415541522
Bug: 346588978
Flag: EXEMPT bugfix
Test: atest RecentsTransitionHandlerTests (more cases to be added later)
Test: Repro steps from b/370682472
Change-Id: I2194d2b69da51fbf03ed22d23ac46fd5e66904b8