[Backport release-26.05] nixos/resolved: apply transformations to keys within resolved section (#544736)

nixos/modules/system/boot/resolved.nix

@@ -30,9 +30,8 @@ let
 
   dnsmasqResolve = config.services.dnsmasq.enable && config.services.dnsmasq.resolveLocalQueries;
 
-  transformSettings =
-    settings:
-    lib.mapAttrs (
+  transformSettings = settings: {
+    Resolve = lib.mapAttrs (
       key: value:
       # concat lists for options that should result in space-separated values
       if
@@ -46,7 +45,8 @@ let
         concatStringsSep " " value
       else
         value
-    ) settings;
+    ) settings.Resolve;
+  };
 
   resolvedConf = settingsToSections (transformSettings cfg.settings);
 in