cflowd - `metering_process` as option

`metering_process` is not working in SR2se.
Making it optional and commenting out in group_vars

geant/gap_ansible/roles/bc_templates/routers/nokia/cflowd.j2

@@ -10,7 +10,9 @@
     <sample-profile>
         <profile-id>{{ profile.id }}</profile-id>
         <sample-rate>{{ profile.sample_rate }}</sample-rate>
+        {% if profile.metering_process is defined %}
         <metering-process>{{ profile.metering_process }}</metering-process>
+        {% endif %}
     </sample-profile>
       {% endfor %}
     {% endif %}