[Search] Sync header Y translation with AllApps y scroll

Instead of calling scrollToTop directly, calling  mHeader.reset scrolls recylcerview to top and reset headerView y translation

Bug: 195365449
Test: enable three button mode, open AllApps, slightly scroll so predictions are partially visible, tap on search box and then outside; verify AllApps is scrolled to top and header is reset appropriately.
Change-Id: I9ba7cf019cb23dd259356243dc2a6294ca5481fe

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

@@ -640,7 +640,7 @@ public class AllAppsContainerView extends SpringRelativeLayout implements DragSo
     public void onClearSearchResult() {
         mIsSearching = false;
         rebindAdapters();
-        getActiveRecyclerView().scrollToTop();
+        mHeader.reset(false);
     }
 
     public void onSearchResultsChanged() {