Merge "Block SHELL_UID from overlay fabricate and clear shell overlays on boot" into sc-dev am: 987cfe1bff am: 073a98e367 am: c5a945385b

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

Change-Id: I7ced3d908e04e1d1fcf28a43a3fc49ca6903b7d2