Cleanup params in jenkins jobs

Change-Id: I5400aadc63a11d54310975a1d4d722c9b90dc70b
diff --git a/jenkins/client/job/opencontrail/git-mirrors/downstream.yml b/jenkins/client/job/opencontrail/git-mirrors/downstream.yml
index 1cdb7e8..0cf3a33 100644
--- a/jenkins/client/job/opencontrail/git-mirrors/downstream.yml
+++ b/jenkins/client/job/opencontrail/git-mirrors/downstream.yml
@@ -1,6 +1,6 @@
-classes:
-  - system.jenkins.client.job.common
 parameters:
+  _param:
+    jenkins_pollscm_spec: "H/60 * * * *"
   jenkins:
     client:
       job_template: