The nova-next job is being moved from openstack-zuul-jobs
to the nova repo and so we'll remove it's usage from
project-config, therefore we need to define it's usage for
devstack here.
The related project-config change is:
I36d96f89b3e5323746fcbcef5cc7e4d0384a184d
Depends-On: I24a5f73c29094a23e2fdef8ee8b43601300af593
Change-Id: I28971dc7e5cb0b5cf9698e5251a7bb099e63f3db