Fix bug where all apps scrollbar jumps.

The problem is that rowAppIndex is not being set when we swap in the
new predictions. So when we call AllAppsRecyclerView#getCurrentScrollY,
the "item.rowAppIndex == 0" clause returns true for every predicted app,
which results in a larger than expected value.

Bug: 64628968
Change-Id: I37ca660522b5a99666de2ea0b9c0aa8cd3732aca

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

@@ -362,6 +362,7 @@ public class AlphabeticalAppsList {
         for (int i = 0; i < size; ++i) {
             AppInfo info = apps.get(i);
             AdapterItem appItem = AdapterItem.asPredictedApp(i, "", info, i);
+            appItem.rowAppIndex = i;
             mAdapterItems.set(i, appItem);
             mFilteredApps.set(i, info);
             mAdapter.notifyItemChanged(i);