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.
not sure, as i didn't write any test yet. @bkutil what do you say? does the key of the hash need to be a node object id? if not i will just pass the `pending_node_actions` into `delete_remove_role_from_runlist`