freeipa role uses undefined node_fqdn

This was defined in client with freeipa as:

```yaml
# environments/common/inventory/group_vars/all/defaults.yml:
node_fqdn: "{{ [inventory_hostname, openhpc_cluster_name, cluster_domain_suffix ] | join('.') }}"  # works even without facts unlike ansible_fqdn
```

but I guess this got missed when upstreaming :-(