HIVE-8726: Collect Spark TaskMetrics and build job statistic[Spark Branch] (Chengxiang via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1637199 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8674 Fix tests after merge [Spark Branch] (Brock via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1637223 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8649: Increase level of parallelism in reduce phase [Spark Branch] (Jimmy via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1637255 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8700 : Replace ReduceSink to HashTableSink (or equi.) for small tables [Spark Branch] (Suhas Satish via Szehon)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1637315 13f79535-47bb-0310-9956-ffa450edef68