Add job builds discarder

Change-Id: I7a4a46826b547731b91f2ed1f58927ba4ddd4455
diff --git a/jenkins/client/job/debian/packages/extra.yml b/jenkins/client/job/debian/packages/extra.yml
index 0a21a55..f3475b3 100644
--- a/jenkins/client/job/debian/packages/extra.yml
+++ b/jenkins/client/job/debian/packages/extra.yml
@@ -212,6 +212,11 @@
           template:
             type: workflow-scm
             concurrent: false
+            discard:
+              build:
+                keep_num: 10
+              artifact:
+                keep_num: 10
             scm:
               type: git
               url: "${_param:jenkins_gerrit_url}/mk/mk-pipelines"