Clear salt-keys in baremetal cicd deployments

When a BM lab is re-deployed, cfg01 is bootstrapped first.
But all BM and VCP nodes from previous deployment are still active,
and register their salt-minions once the new salt-master is up.

To prevent deployment errors, before re-deploying MAAS nodes:

- clear all the salt keys and re-register the cfg01 node

Minor fix to VCP nodes:
- add ens2 'role: single_dhcp' to get the node accessible
  from salt-master after reboot

Change-Id: I4f511c32ad40a3c27235abc7cb8330bcc7cb6a50
diff --git a/tcp_tests/templates/cookied-cicd-bm-os-contrail40-maas/salt.yaml b/tcp_tests/templates/cookied-cicd-bm-os-contrail40-maas/salt.yaml
index 4ea0035..a7b3677 100644
--- a/tcp_tests/templates/cookied-cicd-bm-os-contrail40-maas/salt.yaml
+++ b/tcp_tests/templates/cookied-cicd-bm-os-contrail40-maas/salt.yaml
@@ -48,6 +48,17 @@
   retry: {count: 1, delay: 5}
   skip_fail: false
 
+- description: Remove all the salt-minions and re-register the cfg01 minion
+  cmd: |
+    salt-key -y -D;
+    salt-call test.ping
+    sleep 5
+    # Check that the cfg01 is registered
+    salt-key | grep cfg01
+  node_name: {{ HOSTNAME_CFG01 }}
+  retry: {count: 1, delay: 5}
+  skip_fail: false
+
 - description: provision the automatically commissioned physical nodes through MAAS
   cmd: |
     salt-call maas.deploy_machines;