Fix repeated empty workspaces after changing the grid size.

There are specific scenarios when you can force an extra empty
workspace after changing the grid, fortunately there is a
function that removes empty workspaces.

Fix:229349287
Test: Add a widget in a new empty workspace page, change the
grid then remove the widget in the new grid size then return
to the previous grid and it shouldn't have an empty workspace.

Change-Id: I7b73ae2ca058bc84b3b361930e3dc856c045281b

src/com/android/launcher3/Launcher.java

@@ -2742,6 +2742,8 @@ public class Launcher extends StatefulActivity<LauncherState>
         getViewCache().setCacheSize(R.layout.folder_page, 2);
 
         TraceHelper.INSTANCE.endSection(traceToken);
+
+        mWorkspace.removeExtraEmptyScreen(true);
     }
 
     private boolean canAnimatePageChange() {