Fix flaky test
Fix flaky test

gpexpand test set 'optimizer=on' by default and CTAS without 'DISTRIBUTED BY'
clause will create randomly distributed table, that will cause the test flaky.

greenplum-db/gpdb,lisakowen/gpdb,xinzweb/gpdb,adam8157/gpdb,lisakowen/gpdb,adam8157/gpdb,lisakowen/gpdb,50wu/gpdb,adam8157/gpdb,50wu/gpdb,xinzweb/gpdb,lisakowen/gpdb,xinzweb/gpdb,greenplum-db/gpdb,50wu/gpdb,adam8157/gpdb,adam8157/gpdb,adam8157/gpdb,greenplum-db/gpdb,50wu/gpdb,50wu/gpdb,adam8157/gpdb,xinzweb/gpdb,xinzweb/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,50wu/gpdb,lisakowen/gpdb,lisakowen/gpdb,greenplum-db/gpdb,xinzweb/gpdb,adam8157/gpdb,lisakowen/gpdb,50wu/gpdb,greenplum-db/gpdb,xinzweb/gpdb,xinzweb/gpdb,50wu/gpdb,greenplum-db/gpdb,lisakowen/gpdb