Magnum cluster deletion is not behaving as expected. While it appears to
delete successfully, _delete_complete routine in
magnum/drivers/heat/driver.py is never called because the status of
nodegroups have not had the chance to sync with Heat before
_check_delete_complete is called. As a result, for example, trustee user
accounts are left orphaned. This PS changes or order of activities so
that _delete_complete is invoked successfully.
(cherry picked from commit 1cdc0628a28da32ef52324244a4c97b0794c2542)