Add SYSTEM_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS to CalendarDebugActivity am: 11fe2048a5

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/providers/CalendarProvider/+/13545483

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I69fb185a4e5558929be7e6ef14e170d9cdeb7788