Remove key ovverride as it comes from pillars

Change-Id: I0c16fe82a9b07c4d95c87c2a45566e27e6a43022
diff --git "a/\173\173 cookiecutter._env_name \175\175/overrides.yml" "b/\173\173 cookiecutter._env_name \175\175/overrides.yml"
index 9e91ad2..a0b85d8 100644
--- "a/\173\173 cookiecutter._env_name \175\175/overrides.yml"
+++ "b/\173\173 cookiecutter._env_name \175\175/overrides.yml"
@@ -20,7 +20,6 @@
     galera_xtrabackup_parallel: 1
     galera_error_log_enabled: true
     # from system.openssh.client.lab
-    root_private_key: ${_param:cluster_private_key}
   openssh:
     server:
       password_auth: true