Enable the "diego_cnb" flag for "luna"

* for details, see cloudfoundry/community#591

Author: jochenehret

ci/pipelines/cf-deployment.yml

@@ -643,6 +643,7 @@ jobs:
         BBL_STATE_DIR: environments/test/luna/bbl-state
         SYSTEM_DOMAIN: cf.luna.env.wg-ard.ci.cloudfoundry.org
         ENABLED_FEATURE_FLAGS: |
+          diego_cnb
           diego_docker
           task_creation