Add build discarder to some deployment jobs

  - deploy-heat-cicd-lab-dev
  - deploy_kafka_demo
  - deploy-openstack-compute

Change-Id: Ie4d08a1118d880ed32eb008cd9b5aac519040fa7
diff --git a/jenkins/client/job/deploy/openstack.yml b/jenkins/client/job/deploy/openstack.yml
index a9f2007..d5ed556 100644
--- a/jenkins/client/job/deploy/openstack.yml
+++ b/jenkins/client/job/deploy/openstack.yml
@@ -44,6 +44,9 @@
         deploy-openstack-compute:
           type: workflow-scm
           concurrent: true
+          discard:
+            build:
+              keep_num: 50
           display_name: "Deploy - OpenStack Compute node"
           scm:
             type: git