Merge "Block SHELL_UID from overlay fabricate and clear shell overlays on boot" into sc-dev am: 987cfe1bff am: 1a29d2344d am: c61093b21f

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/16077739

Change-Id: Ib5282949f328a4977635985920f3a5a7faf4a062