[CORD-3121] Teardown minikube after helm-api-test, install xos-client in api test

Change-Id: I386c999d0a001aaeed221e0d0663fe6a370a75b7
diff --git a/jjb/pipeline/helm-api-test.groovy b/jjb/pipeline/helm-api-test.groovy
index 4540502..7271d7a 100644
--- a/jjb/pipeline/helm-api-test.groovy
+++ b/jjb/pipeline/helm-api-test.groovy
@@ -130,6 +130,7 @@
          kubectl logs xos-core-api-test
          kubectl delete pod xos-core-api-test
          helm delete --purge xos-core
+         minikube delete
          '''
       deleteDir()
     }