Replaced groups.ipaserver[0] by ansible_fqdn.

Since we are using docker for running the tests we can no longer rely on
groups.ipaserver[0] as the managed host hostname.

tests/host/certificate/test_host_certificate.yml

@@ -21,12 +21,11 @@
 - name: Test host certificates
   hosts: ipaserver
   become: true
-  gather_facts: false
 
   tasks:
   - name: Get Domain from server name
     set_fact:
-      ipaserver_domain: "{{ groups.ipaserver[0].split('.')[1:] | join ('.') }}"
+      ipaserver_domain: "{{ ansible_fqdn.split('.')[1:] | join ('.') }}"
     when: ipaserver_domain is not defined
 
   - name: Host test absent