Move Sunet/Safespring VM's to new site

We're running our VM's at Sunet on what's called "the legacy site" with many known problems. We should move to another site. Sunet will provide a new "project" for us.

There are two ways of doing this: Move or rebuild.

• Moving a VM means something like:
  1. taking a snapshot of the current instance
  2. downloading the snapshot
  3. uploading the snapshot to create a new instance on another site.
• Rebuilding a VM means creating a new instance on another site and reinstalling the VM from scratch. Restoring data can of course be done in any way suitable.

I'd recommend rebuilding, to not have to deal with volume snapshots.

Those are the known VMs hosted at the sunet cluster as of this writing:

• cdn-backend-sunet-01.torproject.org - rebuilt as cdn-backend-sunet-02
• ipv6only.torproject.net - retired, see #40727 (closed)
• build-sunet-a.torproject.net - retired, see #40691 (closed)
• corsicum.torproject.org - new VM created (collector-02.torproject.org), need to be rebuilt, see #41161 (closed)
• nutans.torproject.org - rebuilt as ns5

those are global TODOs:

• enable reverse DNS at new site
• remove old zones