Removing the section break UI support

This was an exploration for an alternative UI in all apps, where we
show section headers before every section. This was never released.

Change-Id: I2d36f1d078cc9a6f3ba6f0ec9655412182c9b016

src/com/android/launcher3/BaseRecyclerViewFastScrollBar.java

@@ -177,10 +177,6 @@ public class BaseRecyclerViewFastScrollBar {
         return mThumbHeight;
     }
 
-    public int getThumbMaxWidth() {
-        return mMaxWidth;
-    }
-
     public boolean isDraggingThumb() {
         return mIsDragging;
     }