Improve system gesture listener to handle display cutout

Expand swipe start threshold such that we can catch touches that just
start below the notch area.

Bug: 123050747
Test: -- 1.Setup a pixel stand.
         2.Verify swipe getsture to dismiss the immersiveModeConfirmation.
      -- atest HeadsUpManagerPhoneTest

Change-Id: Iaad1fbeabf165439667e25f564ae97dee68cb2d5