fix model domains to valid names

Change-Id: Ia89d35ffb204401ac05c11ac877a9a3b69e56745
diff --git a/classes/cluster/sl_k8s_contrail/infra/init.yml b/classes/cluster/sl_k8s_contrail/infra/init.yml
index d5b43d9..cb7e820 100644
--- a/classes/cluster/sl_k8s_contrail/infra/init.yml
+++ b/classes/cluster/sl_k8s_contrail/infra/init.yml
@@ -10,7 +10,7 @@
     infra_config_address: 172.16.10.100
     infra_config_deploy_address: 192.168.10.100
 
-    cluster_domain: sl_k8s_contrail.local
+    cluster_domain: sl-k8s-contrail.local
     cluster_name: sl_k8s_contrail
     apt_mk_version: nightly
   linux: