bundles: various fixes for telegraf plugins

bundles/powerdns/files/pdns.conf

@@ -13,6 +13,9 @@ server-id=${my_hostname}
 
 default-ttl=60
 
+setuid=pdns
+setgid=pdns
+
 % if is_secondary:
 allow-notify-from=${','.join(sorted(my_primary_servers))}
 

bundles/powerdns/metadata.py

@@ -44,6 +44,9 @@ if node.has_bundle('telegraf'):
                 'powerdns': [{}],
             },
         },
+        'additional_groups': {
+            'pdns',
+        },
     }