Setup DB Roles for registry DB in gprd

When the container registry patroni DB cluster is setup, it will just be empty without any special roles or databases needed for container registry, monitoring or pgbouncer.

This issue is for setting up DB, Roles, extensions and functions as needed.

This should be a repeat of what we did in staging already: #1998 (closed)

• create database gitlabhq_registry
• create roles for registry, pgbouncer, monitoring with needed privileges and passwords
• create extensions
• create functions
• configure postgres-exporter and gitlab-monitor appropriately
• configure gitlab-consul to go against the right db