This reduces the clutter of recording files left lying around.

metrics policy was announced here https://trac.torproject.org/projects/tor/ticket/32998#comment:2

A glossary doesn't belong in the tutorial, which expects the user to
know nothing of the service. That belonds in the Howto section, where
we expect to learn a little more about the service before doing things.

I added that TODO based on a misunderstanding of the function of the
private network between the Ganeti nodes. It's not there to provide a
private network between *instances*, but really just the nodes, for
DRBD and Ganeti traffic.

So it makes no sense to allocate private IPs to the instances in that context.

We remove the `gnt-node list` command because it's included in the other.

The rationale is that this part is more rarely used and definitely
more complex than a Howto.