Ensure service is restarted on unit file changes

At the moment we don't restart services if systemd unit file is changed.

We knowingly prevent systemd_service role handlers to execute
by providing `state: started` as otherwise service will be restarted twice.
With that now  we ensure that role handlers will also listen for systemd
unit changes.

Change-Id: I78c9888f7f2b97bd901d9fcce636bc22b6411eb9

handlers/main.yml

@@ -22,6 +22,7 @@
   with_items: "{{ filtered_swift_services }}"
   listen:
     - "venv changed"
+    - "systemd service changed"
 
 - name: Restart rsync service
   service:

vars/main.yml

@@ -22,7 +22,14 @@ filtered_swift_services: |-
   {%   if (value['group'] in group_names) and
            (('service_en' not in value) or
             ('service_en' in value and value['service_en'])) %}
-  {%      set _ = value.update({'service_key': key}) %}
+  {%      set _ = value.update(
+            {
+              'service_key': key,
+              'enabled': value['enabled'] | default(True),
+              'state': value['state'] | default('started')
+            }
+          )
+  %}
   {%      set _ = services.append(value) %}
   {%   endif %}
   {% endfor %}