Migrate to ARM Ubuntu18.04 node

Ubuntu 16.04 still has SSH and Kernel issues.
Migrating to Ubuntu18.04 since we have a good
instance now.

TODO: Disable Ubuntu16.04 arm nodes.
- Currently Ubuntu18.04 arm nodes are under more test.
- No additional costs since no job is using 16.04 arm
  nodes.
- Once confirmed, these will be disabled.

Change-Id: I1ef6dfc04aa6e85531f824e24ad517137a7080ca
Issue-ID: CIMAN-33
Signed-off-by: Jessica Wagantall <jwagantall@linuxfoundation.org>
diff --git a/jjb/policy/policy-pap.yaml b/jjb/policy/policy-pap.yaml
index d5f183e..2bc95a3 100644
--- a/jjb/policy/policy-pap.yaml
+++ b/jjb/policy/policy-pap.yaml
@@ -16,7 +16,7 @@
           docker-pom: 'pom.xml'
           mvn-profile: 'docker'
           mvn-params: '-P docker -Ddocker.pull.registry=docker.io -Ddocker.push.registry=registry-1.docker.io'
-          build-node: ubuntu1604-docker-arm64-4c-2g
+          build-node: ubuntu1804-docker-arm64-4c-2g
           pattern: 'do_not_match_any_file'
       - gerrit-maven-stage:
           sign-artifacts: true
@@ -28,7 +28,7 @@
           build-node: ubuntu1804-docker-8c-8g
       - gerrit-maven-docker-stage:
           project-name: 'policy-pap-arm64'
-          build-node: ubuntu1604-docker-arm64-4c-2g
+          build-node: ubuntu1804-docker-arm64-4c-2g
           maven-versions-plugin: true
           mvn-params: '-P docker -Dmaven.test.skip=true -Ddocker.pull.registry=docker.io -Ddocker.push.registry=registry-1.docker.io'
           container-public-registry: 'docker.io'