Migrate 'make run' to a single-node qeneth instance

[troglobit]

Another day another inconsistency between the Qemu parameters passed to make run and the Qemu parameters in make test passed via Qeneth to Qemu ... *sigh*

Me and @wkz today discussed how we could fix all these annoyances by migrating make run (which is the odd one out here) to instead use a single-node Qeneth topology.

As an added bonus, provided we compute everything at build-time, we could ship releases with multiple topologies, even customer builds could have representative virtual topologies that could be used for deployment in their test labs.

Even the future documentation could reference the Qeneth topologies, e.g., "see this example OSPF topology, which is used by the regression tests."