In the installer, we're beginning to use settings.yaml to populate settings in Foreman, rather than using foreman-config (because it's slow).

What we'd like is for values configured in settings.yaml to overwrite any values currently set in "Setting" records, while at the moment, the settings.yaml file is only used to initialise new settings (a kind of default value).

To prevent users getting confused, I'd expect the UI to prevent users from changing values set via settings.yaml and to inform them why the setting is "locked".