Fix service removal condition

In order to remove service currently we need to satisfy one of
conditions:

- haproxy_backend_nodes and haproxy_backup_nodes are empty and defined
but must be defined
- haproxy_service_enabled is False
- state is absent

There's big issue with logic regarding haproxy_backend_nodes and
haproxy_backup_nodes since they both should be defined and empy,
but in case haproxy_backup_nodes is not defined but haproxy_backend_nodes
is empty we should consider this as condition for removal as well.
But this will make it too complicated.

This change suggest consider rely only on haproxy_service_enabled and
state keys of haproxy_service_configs, as it's sufficient to
drop service based on these 2 options.

Change-Id: Ib37445ad852bcbd8d44d9eda9293565a4e52262b

tasks/haproxy_service_config.yml

@@ -37,11 +37,7 @@
   notify: Regenerate haproxy configuration
   with_items: "{{ haproxy_service_configs }}"
   when:
-    - ((item.service.haproxy_backend_nodes is defined and
-      item.service.haproxy_backend_nodes | length == 0) and
-      (item.service.haproxy_backup_nodes is defined and
-      item.service.haproxy_backup_nodes | length == 0)) or
-      (not ((item.service.haproxy_service_enabled | default('True')) | bool)) or
+    - ((item.service.haproxy_service_enabled | default('True')) | bool) is falsy or
       (item.service.state is defined and item.service.state == 'absent')
   tags:
     - haproxy-service-config