random-seed: don't refresh EFI random seed from random-seed.c anymore

random-seed: don't refresh EFI random seed from random-seed.c anymore

The ESP is simply not mounted early enough for this. We want that the
regular random seed handling runs as early as we possibly could, but we
don't want to delay this until the ESP is actually mounted.

Hence, let's remove this from random-seed.c here. A follow-up commit
will then add this back in, in a separate service which just calls
"bootctl random-seed".

Effectively reverts: f913c784ad4c93894fd6cb2590738113dff5a694

Fixes: #25769