Closes: team#41296

This will typically be `grml` if we're booted in there and haven't
changed the hostname yet, but that's better than a hardcoded
`fsn-node-04`.

- The admin pin is different from the default pin
- Immediately after importing the public key into the temporary, empty
  GNUPGHOME, there will not be any secret keys, until they have been imported

First, use clearer units (GiB instead of G). Then use the k prefix so
it's clearer the connexion between the "1GiB" and the "1024". That way
it's also easy to do, say, a 4GiB swap partition (4k instead of 4096).