We don't need these 2 roughly-the-same settings related to the
traefik-certs-dumper role.

For Traefik, it makes sense, because it's a component used by the
various related playbooks and they could step onto each other's toes
if the role is enabled, but Traefik is disabled (in that case, uninstall
tasks will run).

As for Traefik certs dumper, the other related playbooks don't have it,
so there's no conflict. Even if they used it, each one would use its own
instance (different `devture_traefik_certs_dumper_identifier`), so there
wouldn't be a conflict and uninstall tasks can run without any danger.