delete _remove roles from the run_list

When a `$barclamp-$role_remove` role (and its removal recipe) has successfully finished, delete it from the node's run_list.
Before this, i had it within the `delete_remove_role_from_runlist` logic, I took it out by suggestion to make testing more easy, by not having to pass the `pending_node_actions` into the method. How would you do it?