Fix: AODH sort rabbitmq hosts pre-task should use 'aodh_all' group

When performing the "Sort rabbitmq hosts" pre-task, the Aodh playbook
should reference the 'aodh_all' group instead of 'metering-alarm_all'.

Closes-Bug: #1553370
Change-Id: I57235cc5eb12db7aeb48518b4bf0d7e6f16f363d

playbooks/os-aodh-install.yml

@@ -44,7 +44,7 @@
     - name: Sort the rabbitmq servers
       dist_sort:
         value_to_lookup: "{{ container_name }}"
-        ref_list: "{{ groups['metering-alarm_all'] }}"
+        ref_list: "{{ groups['aodh_all'] }}"
         src_list: "{{ rabbitmq_servers }}"
       register: servers
     - name: Set rabbitmq servers