remove logger

packages/app/src/server/service/activity.ts

@@ -1,12 +1,7 @@
 import { getModelSafely } from '@growi/core';
 
-import loggerFactory from '~/utils/logger';
-
 import Crowi from '../crowi';
 
-
-const logger = loggerFactory('growi:service:activity');
-
 class ActivityService {
 
   crowi!: Crowi;