Fix screen will flicker when swipe-down around NavigationBar to

trigger One-Handed mode many times quickly in a short time

To prevent entering or exiting OHM quilcky in a shot time.

Bug: 185304468
Test: manual
Test: atest WMShellUnitTests
Change-Id: Ibc5ade564da241d5871b3b037c97bd68a6b03a5d