Enable sandbox execution

Change-Id: I78aeaae5b4f034a77680c03dce511a78231656b7
diff --git a/jjb/templates/artifact-release.yml b/jjb/templates/artifact-release.yml
index 2cff260..479ad5d 100644
--- a/jjb/templates/artifact-release.yml
+++ b/jjb/templates/artifact-release.yml
@@ -52,6 +52,7 @@
 
     project-type: pipeline
     concurrent: true
+    sandbox: true
 
     dsl: !include-raw-escape: ../pipeline/artifact-release.groovy