Revert "Remove temp user creation activity"

Revert submission 17073604-presubmit-am-787ed0a55f5040968a8a9c14764ddd01

Reason for revert: cause of b/222711091
Reverted Changes:
I3aae23a57:Remove temp user creation activity
I6b2ce8e01:Scrim was flickering on FPS unlock

Change-Id: I7dcea569feaae4f03b634a13b3a33c3b45abeb53