Attempt to fix DisplayCutoutTests flakiness

Case 1: Unexpected timeout. It can’t get the window focus after launch
        the activity during the the screen off.

Case 2: Sometimes the navigation bar does not hide. The hide flags may
        be cleared during the testing. Set the flags when window gets
        focus to fix this flaky test.

Bug: 120182818
Test: atest DisplayCutoutTests
Change-Id: I3f97d67256c153176c00d483987d3e9f87a0a936
2 files changed