Fix divider bar not shown when entering split with rotation transition

When launching tasks into split with rotation transition, launch won't
handle divider bar fade-in animation because wm-shell will re-render a
new divider bar to apply new rotation config. This makes sure to clear
the divider bar remote animating flag before re-rendering the divider
bar for rotation so wm-shell can finish showing divider bar after
re-rendered it.

Fix: 232043721
Test: enter split with rotation transition, verified divider bar shown.
Change-Id: Ia3040c08b897716fa9a480f2aaf1b06a76daccb4

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

@@ -980,6 +980,9 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
                 updateUnfoldBounds();
                 return;
             }
+            // Clear the divider remote animating flag as the divider will be re-rendered to apply
+            // the new rotation config.
+            mIsDividerRemoteAnimating = false;
             mSplitLayout.update(null /* t */);
             onLayoutSizeChanged(mSplitLayout);
         }