Fix the cutout of magnification border

If the window is unmagnifiable, it might cause the cutout of
magnification region.
To fix it, we set the flag when the touchable region is not the
entier window frame.

To fix NexusLauncherTests, we add a flag to avoid updateViewLayout
too frequently that would impact memory test and have the performance
issue.

Bug: 196510717
Test: manual test on gestural and 3-button navigation
      presumbit test pass
      run atest NexusLauncherTests with foldables
Change-Id: Ifef81640fe6c08ee1b0dcd3915227fba3002ea43