[placement][nova][ptg] Resourceless trait filters
> So we have a specific use case: COMPUTE_TRUSTED_CERTS + NUMA requires
> placement to support traits on RPs that are not providing resources.
> Will in this case VCPU and MEMORY_MB always requested in the unnumbered
> group still? Or there are cases when those resources are requested in a
> numbered group?
That'll depend on the outcome of the various NUMA modeling discussions;
but as soon as we need to be able to request resources from more than
one NUMA node, it seems certain that we'll need to use numbered groups.