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/lab/demo.yml b/jenkins/client/job/deploy/lab/demo.yml
index 2bb6ad5..3af2d7c 100644
--- a/jenkins/client/job/deploy/lab/demo.yml
+++ b/jenkins/client/job/deploy/lab/demo.yml
@@ -5,6 +5,9 @@
         deploy_kafka_demo:
           type: workflow-scm
           concurrent: false
+          discard:
+            build:
+              keep_num: 10
           display_name: "Kafka demo"
           scm:
             type: git