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: I69570b7d40c8487a3f37b32c34ca79b1cb1762dd