Backport HIVE-19104: Use independent warehouse directories in test metastores.

TestHS2ImpersonationWithRemoteMS fails on branch-3. It makes assertions about the state of the warehouse directory, but it doesn't account for a part of metastore initialization that updates the warehouse directory to parameterize it by port number for test isolation.

MetaStoreTestUtils#startMetaStoreWithRetry sets the warehouse directory as the new metastore.warehouse.dir property. AbstractHiveService#get/setWareHouseDir later works with the deprecated hive.metastore.warehouse.dir property. MetastoreConf will take care of resolving requests for the new property to values under the old property, but not vice versa.

On master, HIVE-19104 included an additional line in MiniHs2 to make sure these 2 properties would stay in sync for test runs. This issue tracks a slightly modified backport of that patch to branch-3.