[nova] Intermittent gate failures in functional tests

In case you're seeing a bunch of nova versioned notification functional tests failing this week, it's being tracked [1] and there is a skip patch approved [2] to hopefully resolve it while a long-term fix is worked.

[1] http://status.openstack.org/elastic-recheck/#1839515 [2] https://review.opendev.org/#/c/675417