Set optimizer GUC to on by default
Set optimizer GUC to on by default

When the GPDB is build with GPORCA, `optimizer` GUC is set to on
by default. If GPDB is not build with GPORCA this guc is off by default.

Signed-off-by: Omer Arap <ce790f0f17dfa06c748b253b0854bcc0f9abba97@pivotal.io>

cjcjameson/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,yuanzhao/gpdb,rvs/gpdb,janebeckman/gpdb,yuanzhao/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,Quikling/gpdb,adam8157/gpdb,yuanzhao/gpdb,rvs/gpdb,Chibin/gpdb,edespino/gpdb,lisakowen/gpdb,xinzweb/gpdb,janebeckman/gpdb,Quikling/gpdb,adam8157/gpdb,yuanzhao/gpdb,kaknikhil/gpdb,lisakowen/gpdb,greenplum-db/gpdb,lisakowen/gpdb,jmcatamney/gpdb,50wu/gpdb,xinzweb/gpdb,Quikling/gpdb,Quikling/gpdb,Chibin/gpdb,jmcatamney/gpdb,cjcjameson/gpdb,edespino/gpdb,janebeckman/gpdb,xinzweb/gpdb,janebeckman/gpdb,Quikling/gpdb,jmcatamney/gpdb,ashwinstar/gpdb,50wu/gpdb,xinzweb/gpdb,cjcjameson/gpdb,janebeckman/gpdb,janebeckman/gpdb,rvs/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,Quikling/gpdb,greenplum-db/gpdb,edespino/gpdb,edespino/gpdb,lisakowen/gpdb,50wu/gpdb,Chibin/gpdb,xinzweb/gpdb,rvs/gpdb,kaknikhil/gpdb,adam8157/gpdb,rvs/gpdb,greenplum-db/gpdb,Quikling/gpdb,edespino/gpdb,greenplum-db/gpdb,edespino/gpdb,Chibin/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,xinzweb/gpdb,kaknikhil/gpdb,Chibin/gpdb,lisakowen/gpdb,jmcatamney/gpdb,janebeckman/gpdb,rvs/gpdb,janebeckman/gpdb,janebeckman/gpdb,kaknikhil/gpdb,adam8157/gpdb,xinzweb/gpdb,cjcjameson/gpdb,ashwinstar/gpdb,adam8157/gpdb,lisakowen/gpdb,cjcjameson/gpdb,kaknikhil/gpdb,jmcatamney/gpdb,50wu/gpdb,cjcjameson/gpdb,rvs/gpdb,cjcjameson/gpdb,yuanzhao/gpdb,kaknikhil/gpdb,Chibin/gpdb,rvs/gpdb,lisakowen/gpdb,adam8157/gpdb,50wu/gpdb,Chibin/gpdb,Chibin/gpdb,adam8157/gpdb,cjcjameson/gpdb,ashwinstar/gpdb,xinzweb/gpdb,Quikling/gpdb,adam8157/gpdb,Chibin/gpdb,yuanzhao/gpdb,edespino/gpdb,yuanzhao/gpdb,kaknikhil/gpdb,lisakowen/gpdb,edespino/gpdb,edespino/gpdb,edespino/gpdb,yuanzhao/gpdb,Quikling/gpdb,kaknikhil/gpdb,50wu/gpdb,Quikling/gpdb,kaknikhil/gpdb,cjcjameson/gpdb,greenplum-db/gpdb,50wu/gpdb,rvs/gpdb,janebeckman/gpdb,rvs/gpdb,50wu/gpdb,yuanzhao/gpdb,kaknikhil/gpdb,greenplum-db/gpdb,yuanzhao/gpdb,Chibin/gpdb,cjcjameson/gpdb