Allow database user to run restart database with gitlab-ctl

Running /opt/gitlab/embedded/bin/pg_ctl restart -w -D /var/opt/gitlab/postgresql/data/ -m {fast,immediate or smart} should restart the database, but with any of those options, it fails to see the database shutdown.

gitlab-psql@db:~$ /opt/gitlab/embedded/bin/pg_ctl restart -w -D /var/opt/gitlab/postgresql/data/ -m fast
waiting for server to shut down............................................................... failed
pg_ctl: server does not shut down
gitlab-psql@db:~$ /opt/gitlab/embedded/bin/pg_ctl restart -w -D /var/opt/gitlab/postgresql/data/ -m immediate
waiting for server to shut down............................................................... failed
pg_ctl: server does not shut down
gitlab-psql@db:~$ /opt/gitlab/embedded/bin/pg_ctl restart -w -D /var/opt/gitlab/postgresql/data/ -m smart
waiting for server to shut down............................................................... failed
pg_ctl: server does not shut down

This should work without error.

/cc @jtevnan