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: I831f6d62f0d31384258571e01a4e7cdd75b73e2c

handlers/main.yml

@@ -27,6 +27,7 @@
   listen:
     - "Restart neutron services"
     - "venv changed"
+    - "systemd service changed"
 
 # NOTE(cloudnull):
 # When installing or upgrading it is possible that an old metadata proxy process will not
@@ -130,6 +131,7 @@
   listen:
     - "Restart neutron services"
     - "venv changed"
+    - "systemd service changed"
 
 - name: start ovn service
   service:

vars/main.yml

@@ -340,7 +340,13 @@ filtered_neutron_services: |-
           (('service_en' not in value) or
            ('service_en' in value and value['service_en'])) and
            not ('wsgi_app' in value and value['wsgi_app']) %}
-  {%     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 %}