Guard slices from being requested by guest user

According to patch of A-231987122, AOSP restricts app to modify relevant
mobile settings when user is a guest. This change intends to prevent the
slices related to mobile settings from being requested by guest user.

Bug: 278616139
Bug: 277333776
Bug: 262244832
Bug: 278616520
Bug: 278615120
Test: robotests
Change-Id: I4dc4bbfdb5cf76e188e6f62ebfd74ef6fa2fe33b

tests/robotests/src/com/android/settings/testutils/shadow/ShadowUserManager.java

@@ -55,6 +55,7 @@ public class ShadowUserManager extends org.robolectric.shadows.ShadowUserManager
     private int[] profileIdsForUser = new int[0];
     private boolean mUserSwitchEnabled;
     private Bundle mDefaultGuestUserRestriction = new Bundle();
+    private boolean mIsGuestUser = false;
 
     private @UserManager.UserSwitchabilityResult int mSwitchabilityStatus =
             UserManager.SWITCHABILITY_STATUS_OK;
@@ -270,4 +271,13 @@ public class ShadowUserManager extends org.robolectric.shadows.ShadowUserManager
             mUserProfileInfos.get(i).flags |= UserInfo.FLAG_ADMIN;
         }
     }
+
+    @Implementation
+    protected boolean isGuestUser() {
+        return mIsGuestUser;
+    }
+
+    public void setGuestUser(boolean isGuestUser) {
+        mIsGuestUser = isGuestUser;
+    }
 }