allowing concurrent builds for voltha-system-tests

Change-Id: I0bf059dd49ba79c6fa44235148f8d6d9834b1210
diff --git a/jjb/voltha-e2e.yaml b/jjb/voltha-e2e.yaml
index 2f095fb..0829a83 100644
--- a/jjb/voltha-e2e.yaml
+++ b/jjb/voltha-e2e.yaml
@@ -141,7 +141,7 @@
           description: 'test tags'
 
     project-type: pipeline
-    concurrent: false
+    concurrent: true
 
     dsl: !include-raw-escape: pipeline/{pipeline}