fix: simple agent: Fix the long-term memory dysfunction

[wangliang181230]

What this PR does / why we need it?

fix: simple agent: Fix the long-term memory dysfunction
简易智能体：修复 读取长期记忆功能不生效 的问题

Summary of your change

修复两种情况：

1. 流式输出时，且未使用MCP时；
2. 非流式输出时。

Please indicate you've done the following:

• Made sure tests are passing and test coverage is added if needed.
• Made sure commit message follow the rule of Conventional Commits specification.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed.