Default DND rules show at top and can't be deleted

Test: make ROBOTEST_FILTER=ZenModeAutomaticRulesPreferenceControllerTest RunSettingsRoboTests -j40
Bug: 63077372
Change-Id: I43e7e2a70df5defe931a7ecedc6f946853dab476

src/com/android/settings/notification/ZenRulePreference.java

@@ -73,6 +73,10 @@ public class ZenRulePreference extends TwoTargetPreference {
 
     @Override
     protected int getSecondTargetResId() {
+        if (mId != null && ZenModeConfig.DEFAULT_RULE_IDS.contains(mId)) {
+            return 0;
+        }
+
         return R.layout.zen_rule_widget;
     }