Prevent guest user from toggling mobile data Quick Setting

Prevents the guest user from toggling mobile data on/off by using the
mobile data quick setting.

The guest user is not able to access the network settings menu where
mobile data is usually toggled. The guest user should therefore not be
able to toggle mobile data on/off by using quick settings.

Bug: 150262422
Test: atest SystemUITests
Change-Id: I24262d4580fa5d7414d5d3e7e0e42873432ab74f

packages/SystemUI/src/com/android/systemui/qs/tiles/CellularTile.java

@@ -25,6 +25,7 @@ import android.content.Intent;
 import android.content.res.Resources;
 import android.os.Handler;
 import android.os.Looper;
+import android.os.UserHandle;
 import android.provider.Settings;
 import android.service.quicksettings.Tile;
 import android.telephony.SubscriptionManager;
@@ -244,7 +245,8 @@ public class CellularTile extends QSTileImpl<SignalState> {
 
     @Override
     public boolean isAvailable() {
-        return mController.hasMobileDataFeature();
+        return mController.hasMobileDataFeature()
+            && mHost.getUserContext().getUserId() == UserHandle.USER_SYSTEM;
     }
 
     private static final class CallbackInfo {