Remove <think> content for `Generate` if it's not stream output. (#5281)

### What problem does this PR solve?

### Type of change

- [x] Refactoring

agent/component/generate.py

@@ -198,6 +198,7 @@ class Generate(ComponentBase):
         if len(msg) < 2:
             msg.append({"role": "user", "content": "Output: "})
         ans = chat_mdl.chat(msg[0]["content"], msg[1:], self._param.gen_conf())
+        ans = re.sub(r"<think>.*</think>", "", ans, flags=re.DOTALL)
 
         if self._param.cite and "content_ltks" in retrieval_res.columns and "vector" in retrieval_res.columns:
             res = self.set_cite(retrieval_res, ans)