Parametrizing the build node to allow for custom ones

Change-Id: Ie051187ef5074881fd32a41223a247f9d38e57ef
diff --git a/jjb/verify/voltha-system-tests.yaml b/jjb/verify/voltha-system-tests.yaml
index 3624903..d3e409f 100644
--- a/jjb/verify/voltha-system-tests.yaml
+++ b/jjb/verify/voltha-system-tests.yaml
@@ -7,15 +7,15 @@
 
     jobs:
       - 'verify-voltha-system-tests-jobs':
-          buildNode: 'ubuntu18.04-basebuild-4c-8g'
+          build-node: 'ubuntu18.04-basebuild-4c-8g'
           branch-regexp: '{all-branches-regexp}'
       - 'verify-voltha-system-tests-jobs-voltha-2.7':
-          buildNode:  'ubuntu18.04-basebuild-4c-8g'
+          build-node:  'ubuntu18.04-basebuild-4c-8g'
           name-extension: '-voltha-2.7'
           override-branch: 'voltha-2.7'
           branch-regexp: '{kind-voltha-regexp}'
       - 'verify-voltha-system-tests-jobs-master':
-          buildNode:  'ubuntu18.04-basebuild-4c-8g'
+          build-node:  'ubuntu18.04-basebuild-4c-8g'
           branch-regexp: '^master$'
 
 - job-group: