Add Barbican user to the list of subcloud users.

Distributed Cloud manager need to know about Barbican user in order
to retrieve its username and password for subclouds configuration in
the config_subcloud script.

Change-Id: I59d5a2fd79a88ba1690b1586fbd0c426d6bc114a
Story: 2003108
Task: 27700
Signed-off-by: Alex Kozyrev <alex.kozyrev@windriver.com>

dcmanager/api/controllers/v1/subclouds.py

@@ -355,7 +355,8 @@ class SubcloudsController(object):
             ('neutron', 'neutron'),
             ('heat_admin', 'heat-domain'),
             ('gnocchi', 'gnocchi'),
-            ('fm', 'fm')
+            ('fm', 'fm'),
+            ('barbican', 'barbican')
         ]
 
         user_list = list()