Migrate to Ubuntu18.04

Migrate to Ubuntu18.04 and deprecate
old unused images ubuntu1604-builder-2c-1g
ubuntu1604-builder-4c-2g

Change-Id: I11a772c5e3f45aa54de7a719651838f1fa638057
Issue-ID: CIMAN-373
Signed-off-by: Jessica Wagantall <jwagantall@linuxfoundation.org>
diff --git a/jjb/lab/lab-templates.yaml b/jjb/lab/lab-templates.yaml
index ff7a59d..234d1fc 100644
--- a/jjb/lab/lab-templates.yaml
+++ b/jjb/lab/lab-templates.yaml
@@ -4,7 +4,7 @@
     description: '{job-desc}'
     disabled: false
     project-type: freestyle
-    build-node: ubuntu1604-builder-2c-1g
+    build-node: ubuntu1804-builder-4c-4g
 
     properties:
       - lf-infra-properties: