Toolkit: Fix Webpack less-loader config (#57950)

packages/grafana-toolkit/src/config/webpack/loaders.ts

@@ -94,7 +94,9 @@ export const getStyleLoaders = () => {
         {
           loader: require.resolve('less-loader'),
           options: {
-            javascriptEnabled: true,
+            lessOptions: {
+              javascriptEnabled: true,
+            },
           },
         },
       ],