feat(sqllab): improve SaveDatasetModal design with proper theme spacing (#34658)

Co-authored-by: Claude <noreply@anthropic.com>

superset-frontend/src/SqlLab/components/SaveDatasetModal/SaveDatasetModal.test.tsx

@@ -67,7 +67,7 @@ describe('SaveDatasetModal', () => {
     render(<SaveDatasetModal {...mockedProps} />, { useRedux: true });
 
     const saveRadioBtn = screen.getByRole('radio', {
-      name: /save as new unimportant/i,
+      name: /save as new/i,
     });
 
     const fieldLabel = screen.getByText(/save as new/i);