[FSSDK-12813] Remove unused UserEvent import in log_event.spec

Author: jaeopt

lib/event_processor/event_builder/log_event.spec.ts

@@ -20,7 +20,7 @@ import {
   buildLogEvent,
 } from './log_event';
 
-import { ImpressionEvent, ConversionEvent, UserEvent } from './user_event';
+import { ImpressionEvent, ConversionEvent } from './user_event';
 import { Region } from '../../project_config/project_config';