refactor(gateway): 使用线程池替换裸协程

- 在 notify、pay_solve、payfor_query 和 settle_service 模块中引入 gopool
- 创建多个线程池实例，用于不同场景的异步任务处理
- 用线程池执行异步任务，以替代直接使用 go 关键字启动协程
- 调整部分代码结构，以适应线程池的使用

go.sum

@@ -4,6 +4,8 @@ github.com/beego/beego/v2 v2.3.2-0.20241006064559-d5830a0fc2ee h1:j+mbzD7idTH1kt
 github.com/beego/beego/v2 v2.3.2-0.20241006064559-d5830a0fc2ee/go.mod h1:5cqHsOHJIxkq44tBpRvtDe59GuVRVv/9/tyVDxd5ce4=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
+github.com/bytedance/gopkg v0.1.2-0.20240828084325-780ca9ee70fb h1:glte+Ka6C5efXn/QlEAE/wwNrvE+3mYo/ce69fpvtrE=
+github.com/bytedance/gopkg v0.1.2-0.20240828084325-780ca9ee70fb/go.mod h1:576VvJ+eJgyCzdjS+c4+77QF3p7ubbtiKARP3TxducM=
 github.com/bytedance/sonic v1.11.7 h1:k/l9p1hZpNIMJSk37wL9ltkcpqLfIho1vYthi4xT2t4=
 github.com/bytedance/sonic v1.11.7/go.mod h1:LysEHSvpvDySVdC2f87zGWf6CIKJcAvqab1ZaiQtds4=
 github.com/bytedance/sonic/loader v0.1.1 h1:c+e5Pt1k/cy5wMveRDyk2X4B9hF4g7an8N3zCYjJFNM=