[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
1 file changed