Add job builds discarder

Change-Id: I7a4a46826b547731b91f2ed1f58927ba4ddd4455
diff --git a/jenkins/client/job/salt-formulas/release.yml b/jenkins/client/job/salt-formulas/release.yml
index fe6df5e..eca83f6 100644
--- a/jenkins/client/job/salt-formulas/release.yml
+++ b/jenkins/client/job/salt-formulas/release.yml
@@ -5,6 +5,11 @@
         release-salt-formulas:
           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"