Secure => global bubble settings pt 2

Follow up to http://ag/8222583
- Replace references to Secure.NOTIFICATION_BUBBLES with
Global.NOTIFICATION_BUBBLES

Fixes: 136034310
Bug: 129158983
Test: m RunSettingsRoboTests
Test: atest SystemUITests
Test: manual - work profile bubbles show up
Change-Id: Ifa71206353237b837cfcda6d23ea6a6ec2c146d0

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

@@ -47,8 +47,8 @@ public class GlobalBubblePermissionObserverMixin extends ContentObserver {
 
     public void onStart() {
         mContext.getContentResolver().registerContentObserver(
-                Settings.Secure.getUriFor(
-                        Settings.Secure.NOTIFICATION_BUBBLES),
+                Settings.Global.getUriFor(
+                        Settings.Global.NOTIFICATION_BUBBLES),
                 false /* notifyForDescendants */,
                 this /* observer */);
     }