CORD-2817 remove corebuilder roles and playbooks

Change-Id: I83bc7934452c337ace1797ca706e4aa4d5438826
diff --git a/roles/imagebuilder-publish/defaults/main.yml b/roles/imagebuilder-publish/defaults/main.yml
index 551740c..e18c44e 100644
--- a/roles/imagebuilder-publish/defaults/main.yml
+++ b/roles/imagebuilder-publish/defaults/main.yml
@@ -18,3 +18,4 @@
 deploy_docker_registry: ""
 deploy_docker_tag: "candidate"
 
+build_docker_tag: "candidate"