This reverts commit 05958b228b.
Issue https://github.com/NixOS/nixpkgs/issues/188998 is concerns quite a
few NixOS users with full disk encryption and custom keymap.
Since there hasn't been a proper fix agreed upon and merged, I am
reverting this.
The changes can be applied again, when it is ensured that they do not
break custom keymaps in initrd.