test(app-config): remove redundant virtual attributes test case

packages/backend/src/models/__snapshots__/app-config.test.js.snap

@@ -39,5 +39,3 @@ exports[`AppConfig model > jsonSchema should have correct validations 1`] = `
   "type": "object",
 }
 `;
-
-exports[`AppConfig model > virtualAttributes should return correct properties 1`] = `null`;

packages/backend/src/models/app-config.test.js

@@ -32,10 +32,6 @@ describe('AppConfig model', () => {
     expect(relationMappings).toStrictEqual(expectedRelations);
   });
 
-  it('virtualAttributes should return correct properties', () => {
-    expect(AppConfig.virtualAttributes).toMatchSnapshot();
-  });
-
   describe('connectionAllowed', () => {
     it('should return true when app is enabled, shared and allows custom connection with an active app auth client at least', async () => {
       await createAppAuthClient({