[vitess]Change commit from async to sync

In applyMutation, tx.commit(ctx) is async and doesn't wait for it. Add checkedGet to it.

vitess/src/main/java/com/yahoo/ycsb/db/VitessClient.java

@@ -139,7 +139,7 @@ private Status applyMutation(QueryCreator.Query query) {
         tx.executeKeyspaceIds(
             ctx, query.getQuery(), query.getKeyspace(), query.getKeyspaceId(),
             query.getBindVars(), query.getTabletType()).checkedGet();
-        tx.commit(ctx);
+        tx.commit(ctx).checkedGet();
       }
     } catch (Exception e) {
       e.printStackTrace();