fix(tests): drop removed useLegacyApi prop from ChartRenderer test metadata

The legacy-pipeline removal deleted useLegacyApi from ChartMetadataConfig;
the enableNoResults test still passed it, breaking tsc in lint-frontend.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

superset-frontend/src/components/Chart/ChartRenderer.test.tsx

@@ -162,7 +162,6 @@ test('honors enableNoResults: false from the chart metadata (e.g. self-fetching
     new ChartMetadata({
       name: 'chart that fetches its own data',
       thumbnail: '.png',
-      useLegacyApi: false,
       enableNoResults: false,
     }),
   );