1.1 Enable PostgreSQL replication for staging.gitlab.com

geo-dr-01-db-gstg.c.gitlab-staging-1.internal has been provisioned, but the replication is not working successfully. We need to understand what is not working and figure out how to correct this.

Ideally we should aim to use the same replication method as production. However, if this is not possible this should not be considered a blocker.