Only dump allowed/available shards for existing services

roles/accountserver/templates/config.yml.j2

@@ -48,10 +48,10 @@ http_server:
 
 {% macro dump_shards(resource_type, service_group='all') %}
     {{ resource_type }}:
-{% for h in groups[service_group]|sort %}
-{% if hostvars[h].get('shard_id') %}
+{% for h in groups.get(service_group, [])|sort if hostvars[h].get('shard_id') %}
       - "{{ hostvars[h]['shard_id'] }}"
-{% endif %}
+{% else %}
+      - "NONE"
 {% endfor %}
 {% endmacro %}