[Ongoing Call] Only listen for the swipe gesture while in immersive

mode.

Test: manual: Do a swipe up on the status bar while not in immersive,
then open a landscape immersive app and verify the status bar still
shows (i.e. it wasn't dismissed by the previous swipe)
Test: new unit tests
Bug: 195839150

Change-Id: I1913c25c29b635979b0cb89d815b2d2c6cc40530