Update Portal verify jobs to Ubuntu 1804

Issue-ID: PORTAL-868
Change-Id: I8b38c52f4ae2fba4b4066bc23c0735259c092532
Signed-off-by: statta <statta@research.att.com>
diff --git a/jjb/portal/portal-docker.yaml b/jjb/portal/portal-docker.yaml
index a45188d..6f896ad 100644
--- a/jjb/portal/portal-docker.yaml
+++ b/jjb/portal/portal-docker.yaml
@@ -20,7 +20,7 @@
     mvn-settings: 'portal-settings'
     files: '**'
     archive-artifacts: ''
-    build-node: ubuntu1604-docker-8c-8g
+    build-node: ubuntu1804-docker-8c-8g
     extra-project: 'portal/sdk'
     extra-branch: '{branch}'
     extra-refspec: 'refs/heads/{branch}'