Clean up ShadowUserManager

Remove addManagedUser() and use default shadow for the same purpose.

Test: make RunSettingsRoboTests -j40 ROBOTEST_FILTER=Redaction
Change-Id: I2f86bd51bccbde23a8a37d19b28e30cadb2b9f93

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

@@ -98,15 +98,6 @@ public class ShadowUserManager extends org.robolectric.shadows.ShadowUserManager
         mRestrictionSources.put(restrictionKey + userHandle.getIdentifier(), enforcers);
     }
 
-    @Implementation
-    protected boolean isManagedProfile(@UserIdInt int userId) {
-        return mManagedProfiles.contains(userId);
-    }
-
-    public void addManagedProfile(int userId) {
-        mManagedProfiles.add(userId);
-    }
-
     @Implementation
     protected boolean isQuietModeEnabled(UserHandle userHandle) {
         return mIsQuietModeEnabled;