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

packages/SystemUI/src/com/android/systemui/statusbar/policy/UserSwitcherController.java

@@ -584,6 +584,13 @@ public class UserSwitcherController implements Dumpable {
                 .setPackage(mCreateSupervisedUserPackage)
                 .addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
 
+        // TODO(b/209659998): [to-be-removed] fallback activity for supervised user creation.
+        if (mContext.getPackageManager().resolveActivity(intent, 0) == null) {
+            intent.setPackage(null)
+                    .setClassName("com.android.settings",
+                        "com.android.settings.users.AddSupervisedUserActivity");
+        }
+
         mContext.startActivity(intent);
     }