pg_upgrade:  remove reference to autovacuum_multixact_freeze_max_age
pg_upgrade:  remove reference to autovacuum_multixact_freeze_max_age

autovacuum_multixact_freeze_max_age was added as a pg_ctl start
parameter in 9.3.X to prevent autovacuum from running.  However, only
some 9.3.X releases have autovacuum_multixact_freeze_max_age as it was
added in a minor PG 9.3 release.  It also isn't needed because -b turns
off autovacuum in 9.1+.

Without this fix, trying to upgrade from an early 9.3 release to 9.4
would fail.

Report by EDB

Backpatch through 9.3

ovr/postgres-xl,yazun/postgres-xl,zeroae/postgres-xl,Postgres-XL/Postgres-XL,ashwinstar/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,ovr/postgres-xl,Postgres-XL/Postgres-XL,Postgres-XL/Postgres-XL,xinzweb/gpdb,zeroae/postgres-xl,50wu/gpdb,greenplum-db/gpdb,xinzweb/gpdb,pavanvd/postgres-xl,oberstet/postgres-xl,50wu/gpdb,oberstet/postgres-xl,lisakowen/gpdb,ovr/postgres-xl,yazun/postgres-xl,yazun/postgres-xl,adam8157/gpdb,greenplum-db/gpdb,lisakowen/gpdb,ashwinstar/gpdb,pavanvd/postgres-xl,50wu/gpdb,xinzweb/gpdb,adam8157/gpdb,Postgres-XL/Postgres-XL,lisakowen/gpdb,jmcatamney/gpdb,xinzweb/gpdb,techdragon/Postgres-XL,jmcatamney/gpdb,lisakowen/gpdb,lisakowen/gpdb,oberstet/postgres-xl,ovr/postgres-xl,adam8157/gpdb,50wu/gpdb,techdragon/Postgres-XL,adam8157/gpdb,pavanvd/postgres-xl,greenplum-db/gpdb,lisakowen/gpdb,lisakowen/gpdb,pavanvd/postgres-xl,jmcatamney/gpdb,techdragon/Postgres-XL,greenplum-db/gpdb,xinzweb/gpdb,greenplum-db/gpdb,xinzweb/gpdb,xinzweb/gpdb,zeroae/postgres-xl,ashwinstar/gpdb,jmcatamney/gpdb,Postgres-XL/Postgres-XL,techdragon/Postgres-XL,ashwinstar/gpdb,zeroae/postgres-xl,jmcatamney/gpdb,50wu/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,50wu/gpdb,ovr/postgres-xl,adam8157/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,yazun/postgres-xl,jmcatamney/gpdb,adam8157/gpdb,adam8157/gpdb,zeroae/postgres-xl,50wu/gpdb,yazun/postgres-xl,oberstet/postgres-xl,xinzweb/gpdb,lisakowen/gpdb,techdragon/Postgres-XL,pavanvd/postgres-xl,ashwinstar/gpdb,greenplum-db/gpdb,50wu/gpdb,oberstet/postgres-xl,adam8157/gpdb