Enable maintainerless warnings by default

Author: infinisil

pkgs/top-level/config.nix

@@ -522,10 +522,10 @@ in
         kind = "removal";
         handler = "warn";
       }
-      (lib.mkIf (lib.elem "maintainerless" config.showDerivationWarnings) {
+      {
         kind = "maintainerless";
         handler = "warn";
-      })
+      }
     ];
   };