Allow auth on jenkins, split slave system

Change-Id: I35416dcd6baaa0159f2191be9b4029228545aa53
diff --git a/jenkins/client/credential/gerrit.yml b/jenkins/client/credential/gerrit.yml
index 3b7eb0c..b42f5af 100644
--- a/jenkins/client/credential/gerrit.yml
+++ b/jenkins/client/credential/gerrit.yml
@@ -1,7 +1,9 @@
 parameters:
+  _param:
+    gerrit_admin_user: admin
   jenkins:
     client:
       credential:
         gerrit:
-          username: admin
+          username: ${_param:gerrit_admin_user}
           key: ${_param:gerrit_admin_private_key}