HIVE-8685 DDL operations in WebHCat set proxy user to null in unsecure mode (Eugene Koifman, reviewed by Thejas M Nair)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/branch-0.14@1636024 13f79535-47bb-0310-9956-ffa450edef68