Fix bouncer swipe touch handler

This fix takes the direction of the swipe into account, depending on if
the bouncer is showing or not. This prevents downward swipes from
showing the bouncer.

Test: atest BouncerSwipeTouchHandlerTest
Test: manually on device
Bug: 224996347
Change-Id: I33a7bbd0ca466bdb3412103454d7a2ad57cdcd09