Play fallback animation if icon in All Apps is covered by header.

Bug: 230707341
Test: enter all apps
      scroll so icon is covered by header
      open app, swipe back to return to all apps
      confirm fallback animation plays

      repeat but scroll so icon is not covered by header
      confirm normal animation plays

Change-Id: I56cda07f3eccc11e8909f7fb28210f65cc6e0f1d

src/com/android/launcher3/allapps/ActivityAllAppsContainerView.java

@@ -239,7 +239,7 @@ public class ActivityAllAppsContainerView<T extends Context & AppLauncher
     }
 
     @Override
-    protected int getHeaderBottom() {
+    public int getHeaderBottom() {
         if (FeatureFlags.ENABLE_FLOATING_SEARCH_BAR.get()) {
             return super.getHeaderBottom();
         }