kiel: Rename kiel2 to kiel3, remove old kiel3.

The former Kiel3 host is going to be dropped, since the host known
as kiel2 is locally known as vpn3 it is sound for our numbering scheme
to rename it in this way.
kiel: The private keys of kiel4 are lost.

Furthermore the host is no longer available.
kiel: Update dynamic domain name