Ensure that first/last host detection is deterministic

With ansible-core 2.16 a breaking changes landed [1] to some filters
making their result returned in arbitrary order. With that, we were
relying on them to always return exactly same ordered lists.

With that we need to ensure that we still have determenistic behaviour
where this is important.

[1] https://github.com/ansible/ansible/issues/82554

Depends-On: https://review.opendev.org/c/openstack/openstack-ansible/+/927841
Change-Id: I9b0c090d69bd9a86da9f8d877a4c561b22f8a028

tasks/main.yml

@@ -90,8 +90,7 @@
         - common-mq
         - zun-config
   when:
-    - "zun_services['zun-api']['group'] in group_names"
-    - "inventory_hostname == ((groups[zun_services['zun-api']['group']] | intersect(ansible_play_hosts)) | list)[0]"
+    - _zun_is_first_play_host
   vars:
     _oslomsg_rpc_setup_host: "{{ zun_oslomsg_rpc_setup_host }}"
     _oslomsg_rpc_userid: "{{ zun_oslomsg_rpc_userid }}"
@@ -128,8 +127,7 @@
           - username: "{{ zun_galera_user }}"
             password: "{{ zun_galera_password }}"
   when:
-    - "zun_services['zun-api']['group'] in group_names"
-    - "inventory_hostname == ((groups['zun_api'] | intersect(ansible_play_hosts)) | list)[0]"
+    - _zun_is_first_play_host
   tags:
     - always
 
@@ -169,8 +167,7 @@
         type: "{{ zun_service_type }}"
         description: "{{ zun_service_description }}"
   when:
-    - "zun_services['zun-api']['group'] in group_names"
-    - "inventory_hostname == ((groups['zun_api'] | intersect(ansible_play_hosts)) | list)[0]"
+    - _zun_is_first_play_host
   tags:
     - always
 

tasks/zun_post_install.yml

@@ -84,5 +84,4 @@
   become_user: "{{ zun_system_user_name }}"
   changed_when: false
   when:
-    - zun_services['zun-api']['group'] in group_names
-    - inventory_hostname == ((groups['zun_api'] | intersect(ansible_play_hosts)) | list)[0]
+    - _zun_is_first_play_host

vars/main.yml

@@ -13,6 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+_zun_is_first_play_host: >-
+  {{
+    (zun_services['zun-api']['group'] in group_names and
+      inventory_hostname == groups[zun_services['zun-api']['group']] | select('in', ansible_play_hosts) | first) | bool
+  }}
+
 _zun_oslomsg_rpc_vhost_conf: >-
   {{
     (zun_oslomsg_rpc_vhost is string) | ternary(