Remove custom focus logic

Using the system logic for focus handling so that partially visible contents are
properly handled, eg in overview only hotseat is visible
This does changes the focus logic on workspace when both icons and widgets or different sizes
are present, we may consider reviving (parts of) this logic in the future

Bug: 80189843
Change-Id: I874e284e0a62b579c24d36db9b74da3de7a7e367

src/com/android/launcher3/FocusHelper.java

@@ -65,6 +65,9 @@ class FullscreenKeyEventListener implements View.OnKeyListener {
     }
 }
 
+/**
+ * TODO: Reevaluate if this is still required
+ */
 public class FocusHelper {
 
     private static final String TAG = "FocusHelper";