SystemUI: Move DT2S from PulsingGestureListener

PulsingGestureListener should handle the touch events in the
dozing state (AOD/ambient).
Our DT2S should work in non-dozing mode so move out from here.

Test:
Double tap to sleep on QQS status bar works fine as before.

Change-Id: Ia79df2eb73e54d8b0dcb1d10b18539f4e88a0a18