nixos/locate: remove `nixpkgs.config` usage

nixos/modules/misc/locate.nix

···
         plocate = (mkIf isPLocate (mkMerge [ common plocate ]));
       };
 
-    nixpkgs.config = { locate.dbfile = cfg.output; };
-
-    environment.systemPackages = [ cfg.locate ];
+    environment.systemPackages = [ (cfg.locate.override { dbfile = cfg.output; }) ];
 
     environment.variables = mkIf (!isMorPLocate) { LOCATE_PATH = cfg.output; };
 

pkgs/tools/misc/mlocate/default.nix

···
-{ lib, stdenv, fetchurl, config }:
+{ lib, stdenv, fetchurl, config, dbfile ? config.locate.dbfile or "/var/cache/locatedb" }:
 
-let
-  dbfile = lib.attrByPath [ "locate" "dbfile" ] "/var/cache/locatedb" config;
-in stdenv.mkDerivation rec {
+stdenv.mkDerivation rec {
   pname = "mlocate";
   version = "0.26";
 

pkgs/tools/misc/plocate/default.nix

···
 , systemd
 , liburing
 , zstd
+, dbfile ? config.locate.dbfile or "/var/cache/locatedb"
 }:
-let
-  dbfile = lib.attrByPath [ "locate" "dbfile" ] "/var/cache/locatedb" config;
-in
 stdenv.mkDerivation rec {
   pname = "plocate";
   version = "1.1.19";