Previously we could sometimes change our signing key, but not
regenerate the certificates (signing->link and signing->auth) that
were signed with it. Also, we would regularly replace our TLS x.509
link certificate (by rotating our TLS context) but not replace our
signing->link ed25519 certificate. In both cases, the resulting
inconsistency would make other relays reject our link handshakes.
Fixes two cases of bug 22460; bugfix on 0.3.0.1-alpha.
