Add updates_mirantis repo to system model

The class itself is not attached to anything.
It should be attached to nodes via cluster modes (infra/init.yml)

Related-bug: PROD-36010
Change-Id: Ibb731ef980c4cd9633a6c6626915eb1c46fb89fc
diff --git a/defaults/linux_system_repo.yml b/defaults/linux_system_repo.yml
index 77dfc4e..d39863f 100644
--- a/defaults/linux_system_repo.yml
+++ b/defaults/linux_system_repo.yml
@@ -7,6 +7,10 @@
     linux_system_repo_update_url: http://mirror.mirantis.com/update/${_param:mcp_version}/
     # Global-hotfix
     linux_system_repo_hotfix_url: http://mirror.mirantis.com/hotfix/${_param:mcp_version}/
+    # Updates.mirantis
+    updates_mirantis_host: updates.mirantis.com
+    updates_mirantis_version: stable
+    updates_mirantis_key_file: updates_mirantis.key
     # Per repos
     linux_system_repo_mcp_cassandra_url: ${_param:linux_system_repo_url}/cassandra/
     linux_system_repo_mcp_glusterfs_url: ${_param:linux_system_repo_url}/glusterfs-${_param:linux_system_repo_mcp_glusterfs_version_number}/