Use index scan on pg_resgroupcapability for resource group
Use index scan on pg_resgroupcapability for resource group

We used to use sequence scan on pg_resgroupcapability for functions that
need to do a full scan of pg_resgroupcapability. Problem is accessing
in this way will take a long time after pg_resgroupcapability table was
updated/deleted million times as our stress tests do, pg_resgroupcapability
was filled of invalid blocks and sequence scan wasted lots of time to bypass
those blocks. Using index scan on it can resolve this problem.

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