emacsPackagesNg: lower priority of elpaPackages

Lowering the priority of melpaStablePackages (#36423) leaves elpaPackages ahead
of melpaPackages; the former carries outdated dependencies which should be
overridden by melpaPackages.

See also: #36423

pkgs/top-level/emacs-packages.nix

@@ -385,9 +385,9 @@ let
 in
   lib.makeScope newScope (self:
     {}
+    // elpaPackages self
     // melpaStablePackages self
     // melpaPackages self
-    // elpaPackages self
     // orgPackages self
     // packagesFun self
   )