Update divider if split transition with display change

When resize then rotate display case, this transition should be
animatePendingSplitWithDisplayChange due to sometimes we start
rotation before the resize transition finished.

In this case, we should update the divider layout too to ensure
it draw on correct position for currect display status.

Fix: 285231670
Test: manual
Test: pass existing tests
Change-Id: Iada83fec6ee612446b4797a07583ee5a3d9ee9cd

libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java

@@ -2499,6 +2499,7 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             // handling to the mixed-handler to deal with splitting it up.
             if (mMixedHandler.animatePendingSplitWithDisplayChange(transition, info,
                     startTransaction, finishTransaction, finishCallback)) {
+                mSplitLayout.update(startTransaction);
                 return true;
             }
         }