I am going to use the *postgresql* group for the dedicated database
servers. The configuration for those machines will be quite a bit
different than for the one existing machine that is a member of that
group already: the Nextcloud server. Rather than undefine/override all
the group-level settings at the host level, I have removed the Nextcloud
server from the *postgresql* group, and updated the `nextcloud.yml`
playbook to apply the *postgresql-server* role itself.
Eventually, I want to move the Nextcloud database to the central
database servers. At that point, I will remove the *postgresql-server*
role from the `nextcloud.yml` playbook.