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

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

Change-Id: I63f3c60cc1f0faa14ff4a8d9c45f8f4a28e2db9d