refactor(push-notifications): 移除推送测试服务模块

删除PushTestService及其相关依赖，该服务用于在应用启动时执行挑战相关的推送测试。移除内容包括：
- 删除push-test.service.ts文件（287行代码）
- 从push-notifications.module.ts中移除PushTestService的导入和注册
- 移除了挑战提醒推送测试、活跃参与者查询等测试功能

此变更简化了推送通知模块结构，移除了仅用于测试目的的代码。

src/push-notifications/push-notifications.module.ts

@@ -7,7 +7,6 @@ import { ApnsProvider } from './apns.provider';
 import { PushTokenService } from './push-token.service';
 import { PushTemplateService } from './push-template.service';
 import { PushMessageService } from './push-message.service';
-import { PushTestService } from './push-test.service';
 import { ChallengeReminderService } from './challenge-reminder.service';
 import { UserPushToken } from './models/user-push-token.model';
 import { PushMessage } from './models/push-message.model';
@@ -43,7 +42,6 @@ import { ChallengeParticipant } from '../challenges/models/challenge-participant
     PushTokenService,
     PushTemplateService,
     PushMessageService,
-    PushTestService,
     ChallengeReminderService,
   ],
   exports: [