systemd: remove systemd-initrd-luks-unl0kr from passthru

IDK what unl0kr is. The tests have been broken on aarch64 since the
beginning and it's not part of systemd. The maintainer of unl0kr can be
responsible for maintaining the unl0kr tests

pkgs/os-specific/linux/systemd/default.nix

@@ -957,7 +957,6 @@ stdenv.mkDerivation (finalAttrs: {
             systemd-initrd-luks-empty-passphrase
             systemd-initrd-luks-password
             systemd-initrd-luks-tpm2
-            systemd-initrd-luks-unl0kr
             systemd-initrd-modprobe
             systemd-initrd-shutdown
             systemd-initrd-simple