app: test fixes for community plugins removal

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/app-next/src/App.test.tsx

@@ -16,11 +16,6 @@
 
 import { renderWithEffects } from '@backstage/test-utils';
 
-jest.mock('@backstage/plugin-graphiql', () => ({
-  ...jest.requireActual('@backstage/plugin-graphiql'),
-  GraphiQLIcon: () => null,
-}));
-
 // Rarely, and only in windows CI, do these tests take slightly more than the
 // default five seconds
 jest.setTimeout(15_000);