Disable stack cleanup

Periodic oscore jobs shouldn't cleanup stacks,
because oscore qa should have time to investigate
test results. Stacks will be cleaned up by separate
job. Also as oscore periodic jobs are running in separate
tenant mcp-oscore-ci this won't affect developers.

Change-Id: I316675cd19bcdecc7ef6d636a7b6a67a755db652
diff --git a/jenkins/client/job/oscore/tests.yml b/jenkins/client/job/oscore/tests.yml
index 298e00e..cc4dc38 100644
--- a/jenkins/client/job/oscore/tests.yml
+++ b/jenkins/client/job/oscore/tests.yml
@@ -48,7 +48,7 @@
                 default: 'core,openstack,ovs'
               STACK_DELETE:
                 type: boolean
-                default: 'true'
+                default: 'false'
                 description: Don't enable it if you need to use the lab after
               STACK_CLEANUP_JOB:
                 type: string