fix: update expected string in test

Signed-off-by: Diana Janickova <djanicko@redhat.com>

Author: djanickova

workspaces/scorecard/plugins/scorecard-backend/src/service/router.test.ts

@@ -605,7 +605,9 @@ describe('createRouter', () => {
 
       expect(result.statusCode).toBe(404);
       expect(result.body.error.name).toBe('NotFoundError');
-      expect(result.body.error.message).toContain('Metric provider with ID');
+      expect(result.body.error.message).toContain(
+        'No metric provider registered',
+      );
     });
 
     it('should return aggregated metrics for a specific metric', async () => {