pki: wireguard: T3642: remove obsolete "delete wireguard keypair" command
pki: wireguard: T3642: remove obsolete "delete wireguard keypair" command

As the keys are now stored inside the CLI configuration and no longer in
a file on the filesystem, this command is no longer required.

vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x