Add DeleteUser/DeleteAllUsers to gatekeeper am: 76b743e8a1 am: bc9e65e432

Original change: https://android-review.googlesource.com/c/platform/system/gatekeeper/+/1559801

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Id050fc8ac1026e0fba70840c1ccc560093c179b4