Do not trigger PiP on tapping on TaskView

Regression from ag/15158868, we should not send onUserLeaveHint on
tapping on the app icon in Recents / Overview.

Video: http://recall/-/aaaaaabFQoRHlzixHdtY/fr0fdecPEned7rMjgdWhCQ
Bug: 198682451
Test: manual, tap on app icon in Recents, see video
Change-Id: I66888a75eec30d7e8ba7e09059399381516812ac