🐛 fix: Optimize requests without historical messages

[sxjeru]

💻 变更类型 | Change Type

• [ ] ✨ feat
• [x] 🐛 fix
• [ ] ♻️ refactor
• [ ] 💄 style
• [ ] 👷 build
• [ ] ⚡️ perf
• [ ] 📝 docs
• [ ] 🔨 chore

🔀 变更说明 | Description of Change

当历史消息数设置为0时，应当不附带任何历史消息，请求中仅需包含本次发送的消息内容即可。

📝 补充信息 | Additional Information

close #4816 close #5154