[SPARK-22846][SQL] Fix table owner is null when creating table throug…

…h spark sql or thriftserver

## What changes were proposed in this pull request?
fix table owner is null when create new table through spark sql

## How was this patch tested?
manual test.
1、first create a table
2、then select the table properties from mysql which connected to hive metastore

Please review http://spark.apache.org/contributing.html before opening a pull request.

Author: xu.wenchun <xu.wenchun@immomo.com>

Closes #20034 from BruceXu1991/SPARK-22846.

sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveClientImpl.scala

@@ -186,7 +186,7 @@ private[hive] class HiveClientImpl(
   /** Returns the configuration for the current session. */
   def conf: HiveConf = state.getConf
 
-  private val userName = state.getAuthenticator.getUserName
+  private val userName = conf.getUser
 
   override def getConf(key: String, defaultValue: String): String = {
     conf.get(key, defaultValue)