Fix delegate_to to use group rather then undercloud

Using delegate_to: undercloud relies on the director host name
being "undercloud". We should instead delegate to the first
host in the "Undercloud" group.

Change-Id: I3560d27deb316100c3c4bf70c609c7367192d44a

deployment/barbican/barbican-api-container-puppet.yaml

@@ -785,7 +785,7 @@ outputs:
                 import_role:
                   name: lunasa_hsm
                   tasks_from: unregister_client
-                delegate_to: undercloud
+                delegate_to: "{{ groups['Undercloud'] | first }}"
                 vars:
                   - map_merge:
                     - {get_param: LunasaVars}

deployment/ipa/ipaservices-baremetal-ansible.yaml

@@ -204,7 +204,7 @@ outputs:
             - name: unregister node from ipa server
               import_role:
                 name: tripleo_ipa_cleanup
-              delegate_to: undercloud
+              delegate_to: "{{ groups['Undercloud'] | first }}"
               vars:
                 tripleo_ipa_keytab: {get_param: IdMNovaKeytab}
                 tripleo_ipa_hosts_to_delete:

deployment/nova/nova-vnc-proxy-container-puppet.yaml

@@ -392,12 +392,12 @@ outputs:
               run_once: true
               changed_when: false
               failed_when: false
-              delegate_to: undercloud
+              delegate_to: "{{ groups['Undercloud'] | first }}"
             - name: Deleting nova-consoleauth
               command: "openstack compute service delete {{ item.ID }}"
               loop: "{{ nova_compute_service_result.stdout | from_yaml | default([]) }}"
               run_once: true
-              delegate_to: undercloud
+              delegate_to: "{{ groups['Undercloud'] | first }}"
               failed_when: false
       external_upgrade_tasks:
         - when: