Disable test_subquery test on hbase.

test_subquery was accidentally enabled for HBase, causing code coverage to fail
because of IMPALA-1179.

Change-Id: I892d966481967af3794c9971a585385e013814ca
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4043
Reviewed-by: Marcel Kornacker <marcel@cloudera.com>
Tested-by: jenkins
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4049
Reviewed-by: Dimitris Tsirogiannis <dtsirogiannis@cloudera.com>