Migrate to ubuntu1804-docker

Migrate the rest of the jobs from
ubuntu1604-docker to ubuntu1804-docker
Remove unused nodes

Issue-ID: CIMAN-373
Change-Id: Idec34497cec90f650336cdd2dcfc8aaae2bcd2ec
Signed-off-by: Jessica Wagantall <jwagantall@linuxfoundation.org>
diff --git a/jjb/externalapi/externalapi-nbi.yaml b/jjb/externalapi/externalapi-nbi.yaml
index 71ca922..f9c6198 100644
--- a/jjb/externalapi/externalapi-nbi.yaml
+++ b/jjb/externalapi/externalapi-nbi.yaml
@@ -17,7 +17,7 @@
           maven-versions-plugin: true
           mvn-params: '-Dmaven.test.skip=true'
       - gerrit-maven-docker-stage:
-          build-node: ubuntu1604-docker-8c-8g
+          build-node: ubuntu1804-docker-8c-8g
           maven-versions-plugin: true
           container-public-registry: 'nexus3.onap.org:10001'
           container-staging-registry: 'nexus3.onap.org:10003'