Parametrizing the build node to allow for custom ones

Change-Id: Ie051187ef5074881fd32a41223a247f9d38e57ef
diff --git a/jjb/voltha-e2e.yaml b/jjb/voltha-e2e.yaml
index d5b8bad..b9d88ef 100755
--- a/jjb/voltha-e2e.yaml
+++ b/jjb/voltha-e2e.yaml
@@ -453,6 +453,7 @@
 - job-template:
     id: 'voltha-patch-test'
     name: 'verify_{project}_sanity-test{name-extension}'
+    build-node: 'ubuntu16.04-basebuild-4c-8g'
     override-branch: '$GERRIT_BRANCH'
     sandbox: true
     build-timeout: 20
@@ -479,7 +480,7 @@
     parameters:
       - string:
           name: buildNode
-          default: 'ubuntu16.04-basebuild-4c-8g'
+          default: '{build-node}'
           description: 'Name of the Jenkins node to run the job on'
 
       - string: