Remove unneeded test since the code no longer has this logic

Signed-off-by: Karan Shah <karan.shah@simplybusiness.co.uk>

plugins/airbrake/src/api/ProductionApi.test.ts

@@ -20,7 +20,6 @@ import mockGroupsData from './mock/airbrakeGroupsApiMock.json';
 import { setupServer } from 'msw/node';
 import { setupRequestMockHandlers } from '@backstage/test-utils';
 import { localDiscoveryApi } from './mock';
-import { NoProjectIdError } from './AirbrakeApi';
 
 describe('The production Airbrake API', () => {
   const productionApi = new ProductionAirbrakeApi(localDiscoveryApi);
@@ -54,10 +53,4 @@ describe('The production Airbrake API', () => {
 
     await expect(productionApi.fetchGroups('123456')).rejects.toThrow();
   });
-
-  it('throws if project ID is empty', async () => {
-    await expect(productionApi.fetchGroups('')).rejects.toThrowError(
-      NoProjectIdError,
-    );
-  });
 });