Modify a hard-code keystone username in neutron and heat.

Changed hard-code keystone username for neutron and heat in the
neutron.conf template and heat.conf template.

TrivialFix

Change-Id: Ibdd1422bd4cae5011f9fc5f4de7dfc58601dca1d

ansible/roles/heat/templates/heat.conf.j2

@@ -44,7 +44,7 @@ auth_type = password
 project_domain_id = default
 user_domain_id = default
 project_name = service
-username = heat
+username = {{ heat_keystone_user }}
 password = {{ heat_keystone_password }}
 
 [trustee]
@@ -54,7 +54,7 @@ auth_plugin = password
 project_domain_id = default
 user_domain_id = default
 project_name = service
-username = heat
+username = {{ heat_keystone_user }}
 password = {{ heat_keystone_password }}
 
 [ec2authtoken]

ansible/roles/neutron/templates/neutron.conf.j2

@@ -40,7 +40,7 @@ project_domain_id = default
 user_domain_id = default
 region_name = {{ openstack_region_name }}
 project_name = service
-username = nova
+username = {{ nova_keystone_user }}
 password = {{ nova_keystone_password }}
 
 [oslo_concurrency]
@@ -65,7 +65,7 @@ auth_type = password
 project_domain_id = default
 user_domain_id = default
 project_name = service
-username = neutron
+username = {{ neutron_keystone_user }}
 password = {{ neutron_keystone_password }}
 
 [oslo_messaging_notifications]