Merge "New property to control virtual a/b user-space snapshots" am: b295d44694 am: ec750298c3 am: 328ce9cccb am: fb1cf1f0c1

Original change: https://android-review.googlesource.com/c/platform/system/sepolicy/+/1885106

Change-Id: Id8f3fd6fa1d3ec243cb8395ec1a88b0ad38e25e0