Pass valid ironic_keystone_username to config

PROD-32759

Change-Id: I419dea57d14a19b9593c52496599abd18f39c921
diff --git a/ironic/api/cluster.yml b/ironic/api/cluster.yml
index e2410fb..4612376 100644
--- a/ironic/api/cluster.yml
+++ b/ironic/api/cluster.yml
@@ -45,3 +45,4 @@
       identity:
         region: ${_param:openstack_region}
         protocol: ${_param:cluster_internal_protocol}
+        user: ${_param:keystone_ironic_username}