Revert "kbd service: use /dev/tty1 for systemd-vconsole-setup"

This reverts commit 0c81594a29d99d9ee9c9c88c680340d56823cfb2.

It's no longer needed since systemd-vconsole-setup enumerates all ttys
until it finds a suitable one since systemd v234.

nixos/modules/tasks/kbd.nix

···
           '') config.i18n.consoleColors}
         '';
 
-        /* XXX: systemd-vconsole-setup needs a "main" terminal. By default
-         * /dev/tty0 is used which wouldn't work when the service is restarted
-         * from X11. We set this to /dev/tty1; not ideal because it may also be
-         * owned by X11 or something else.
-         *
-         * See #22470.
-         */
         systemd.services."systemd-vconsole-setup" =
           { wantedBy = [ "sysinit.target" ];
             before = [ "display-manager.service" ];
             after = [ "systemd-udev-settle.service" ];
             restartTriggers = [ vconsoleConf kbdEnv ];
-            serviceConfig.ExecStart = [
-              ""
-              "${pkgs.systemd}/lib/systemd/systemd-vconsole-setup /dev/tty1"
-            ];
           };
       }