Fix horizon in mcp virtual labs

Change-Id: I13ec1e2386c777fa65231937a2082a049fc6c273
diff --git a/classes/cluster/os-ha-contrail/openstack/dashboard.yml b/classes/cluster/os-ha-contrail/openstack/dashboard.yml
index 1be0a9c..1061456 100755
--- a/classes/cluster/os-ha-contrail/openstack/dashboard.yml
+++ b/classes/cluster/os-ha-contrail/openstack/dashboard.yml
@@ -3,7 +3,7 @@
 - system.linux.system.repo.mcp.openstack
 - system.linux.system.repo.mcp.extra
 - system.linux.system.repo.saltstack.xenial
-- system.horizon.server.cluster
+- system.horizon.server.single
 - system.horizon.server.plugin.contrail
 - system.horizon.server.plugin.overrides
 - cluster.os-ha-contrail