nixos/redis: drop unnecessary dependencies from systemd unit

nixos/modules/services/databases/redis.nix

···
     systemd.services.disable-transparent-huge-pages = {
       enable = config.services.redis.enable;
       description = "Disable Transparent Huge Pages (required by Redis)";
-      after = [ "sysinit.target" "local-fs.target" ];
       before = [ "redis.service" ];
       wantedBy = [ "redis.service" ];
       script = "echo never >/sys/kernel/mm/transparent_hugepage/enabled";