Cleanup SSL certs for PostgreSQL
During a recent failover (production#637 (closed)), we ran into issues with apparently unused SSL certs in /var/opt/gitlab/postgresql/data/server.{key,crt}
. See https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/5842#note_128183853.
We should figure out if those are really not needed and if so remove them all together (from all active database nodes).