Run stats test separately, not as part of a parallel group, to avoid possible failures due to stats collector not updating fast enough under heavy load.  Per report from Jeremy Yoder.
Run stats test separately, not as part of a parallel group, to avoid
possible failures due to stats collector not updating fast enough under
heavy load.  Per report from Jeremy Yoder.

xuegang/gpdb,0x0FFF/gpdb,rubikloud/gpdb,janebeckman/gpdb,randomtask1155/gpdb,cjcjameson/gpdb,foyzur/gpdb,chrishajas/gpdb,cjcjameson/gpdb,kaknikhil/gpdb,tpostgres-projects/tPostgres,xuegang/gpdb,50wu/gpdb,royc1/gpdb,janebeckman/gpdb,0x0FFF/gpdb,lpetrov-pivotal/gpdb,tangp3/gpdb,Chibin/gpdb,ovr/postgres-xl,snaga/postgres-xl,arcivanov/postgres-xl,xuegang/gpdb,rubikloud/gpdb,chrishajas/gpdb,yazun/postgres-xl,snaga/postgres-xl,0x0FFF/gpdb,yuanzhao/gpdb,Quikling/gpdb,adam8157/gpdb,rvs/gpdb,yuanzhao/gpdb,ahachete/gpdb,kaknikhil/gpdb,Quikling/gpdb,ashwinstar/gpdb,kaknikhil/gpdb,xinzweb/gpdb,xuegang/gpdb,ovr/postgres-xl,ashwinstar/gpdb,janebeckman/gpdb,tangp3/gpdb,lintzc/gpdb,lpetrov-pivotal/gpdb,chrishajas/gpdb,Chibin/gpdb,randomtask1155/gpdb,rubikloud/gpdb,foyzur/gpdb,arcivanov/postgres-xl,arcivanov/postgres-xl,kmjungersen/PostgresXL,techdragon/Postgres-XL,yazun/postgres-xl,zeroae/postgres-xl,ashwinstar/gpdb,atris/gpdb,lintzc/gpdb,snaga/postgres-xl,randomtask1155/gpdb,randomtask1155/gpdb,0x0FFF/gpdb,atris/gpdb,lpetrov-pivotal/gpdb,yuanzhao/gpdb,postmind-net/postgres-xl,CraigHarris/gpdb,kmjungersen/PostgresXL,cjcjameson/gpdb,tpostgres-projects/tPostgres,ashwinstar/gpdb,zeroae/postgres-xl,CraigHarris/gpdb,royc1/gpdb,ahachete/gpdb,Postgres-XL/Postgres-XL,edespino/gpdb,lintzc/gpdb,yuanzhao/gpdb,atris/gpdb,Quikling/gpdb,chrishajas/gpdb,randomtask1155/gpdb,oberstet/postgres-xl,rubikloud/gpdb,adam8157/gpdb,zaksoup/gpdb,greenplum-db/gpdb,rubikloud/gpdb,greenplum-db/gpdb,lpetrov-pivotal/gpdb,Chibin/gpdb,cjcjameson/gpdb,kaknikhil/gpdb,foyzur/gpdb,cjcjameson/gpdb,janebeckman/gpdb,arcivanov/postgres-xl,royc1/gpdb,Quikling/gpdb,ahachete/gpdb,greenplum-db/gpdb,pavanvd/postgres-xl,edespino/gpdb,greenplum-db/gpdb,edespino/gpdb,jmcatamney/gpdb,xuegang/gpdb,oberstet/postgres-xl,ashwinstar/gpdb,Postgres-XL/Postgres-XL,oberstet/postgres-xl,chrishajas/gpdb,ashwinstar/gpdb,janebeckman/gpdb,lintzc/gpdb,postmind-net/postgres-xl,pavanvd/postgres-xl,Chibin/gpdb,rvs/gpdb,Chibin/gpdb,lintzc/gpdb,oberstet/postgres-xl,arcivanov/postgres-xl,ovr/postgres-xl,rubikloud/gpdb,randomtask1155/gpdb,lisakowen/gpdb,0x0FFF/gpdb,xuegang/gpdb,Quikling/gpdb,tangp3/gpdb,50wu/gpdb,yuanzhao/gpdb,Postgres-XL/Postgres-XL,lpetrov-pivotal/gpdb,chrishajas/gpdb,atris/gpdb,lintzc/gpdb,ahachete/gpdb,rvs/gpdb,edespino/gpdb,lisakowen/gpdb,0x0FFF/gpdb,ashwinstar/gpdb,xinzweb/gpdb,kaknikhil/gpdb,adam8157/gpdb,cjcjameson/gpdb,arcivanov/postgres-xl,pavanvd/postgres-xl,rvs/gpdb,Quikling/gpdb,kaknikhil/gpdb,rvs/gpdb,janebeckman/gpdb,pavanvd/postgres-xl,50wu/gpdb,jmcatamney/gpdb,rvs/gpdb,ahachete/gpdb,lintzc/gpdb,rvs/gpdb,cjcjameson/gpdb,lpetrov-pivotal/gpdb,ahachete/gpdb,ahachete/gpdb,Chibin/gpdb,kmjungersen/PostgresXL,50wu/gpdb,zaksoup/gpdb,50wu/gpdb,yuanzhao/gpdb,oberstet/postgres-xl,lisakowen/gpdb,jmcatamney/gpdb,tpostgres-projects/tPostgres,cjcjameson/gpdb,royc1/gpdb,lisakowen/gpdb,yuanzhao/gpdb,Postgres-XL/Postgres-XL,lpetrov-pivotal/gpdb,jmcatamney/gpdb,Postgres-XL/Postgres-XL,50wu/gpdb,CraigHarris/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,zaksoup/gpdb,cjcjameson/gpdb,CraigHarris/gpdb,zaksoup/gpdb,ovr/postgres-xl,CraigHarris/gpdb,chrishajas/gpdb,jmcatamney/gpdb,zeroae/postgres-xl,techdragon/Postgres-XL,kaknikhil/gpdb,xinzweb/gpdb,randomtask1155/gpdb,atris/gpdb,randomtask1155/gpdb,adam8157/gpdb,CraigHarris/gpdb,Quikling/gpdb,tangp3/gpdb,postmind-net/postgres-xl,rvs/gpdb,atris/gpdb,xuegang/gpdb,edespino/gpdb,0x0FFF/gpdb,chrishajas/gpdb,edespino/gpdb,yuanzhao/gpdb,tangp3/gpdb,snaga/postgres-xl,jmcatamney/gpdb,kmjungersen/PostgresXL,Chibin/gpdb,Chibin/gpdb,lisakowen/gpdb,edespino/gpdb,tangp3/gpdb,snaga/postgres-xl,greenplum-db/gpdb,royc1/gpdb,tpostgres-projects/tPostgres,yazun/postgres-xl,tangp3/gpdb,lisakowen/gpdb,CraigHarris/gpdb,pavanvd/postgres-xl,edespino/gpdb,janebeckman/gpdb,edespino/gpdb,yazun/postgres-xl,atris/gpdb,kmjungersen/PostgresXL,kaknikhil/gpdb,lintzc/gpdb,xinzweb/gpdb,rvs/gpdb,CraigHarris/gpdb,foyzur/gpdb,xinzweb/gpdb,zaksoup/gpdb,Quikling/gpdb,rvs/gpdb,yazun/postgres-xl,adam8157/gpdb,yuanzhao/gpdb,zaksoup/gpdb,kaknikhil/gpdb,edespino/gpdb,tpostgres-projects/tPostgres,xuegang/gpdb,royc1/gpdb,lintzc/gpdb,adam8157/gpdb,ashwinstar/gpdb,xinzweb/gpdb,zeroae/postgres-xl,rubikloud/gpdb,tangp3/gpdb,ahachete/gpdb,zeroae/postgres-xl,atris/gpdb,jmcatamney/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,royc1/gpdb,xuegang/gpdb,foyzur/gpdb,zaksoup/gpdb,royc1/gpdb,Chibin/gpdb,adam8157/gpdb,postmind-net/postgres-xl,xinzweb/gpdb,greenplum-db/gpdb,postmind-net/postgres-xl,CraigHarris/gpdb,lpetrov-pivotal/gpdb,foyzur/gpdb,janebeckman/gpdb,techdragon/Postgres-XL,techdragon/Postgres-XL,janebeckman/gpdb,Quikling/gpdb,cjcjameson/gpdb,lisakowen/gpdb,50wu/gpdb,rubikloud/gpdb,techdragon/Postgres-XL,Quikling/gpdb,ovr/postgres-xl,Chibin/gpdb,kaknikhil/gpdb,0x0FFF/gpdb,xinzweb/gpdb,foyzur/gpdb,50wu/gpdb,foyzur/gpdb,lisakowen/gpdb,adam8157/gpdb,janebeckman/gpdb,zaksoup/gpdb