Fix agent non stream (#1904)

### What problem does this PR solve?

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

agent/component/base.py

                         upstream_outs.append(pd.DataFrame([{"content": c}]))
                         break
                 break
-            if self.component_name.lower().find("answer") >= 0:
-                if self.get_component_name(u) in ["relevant"]:
-                    continue
-            else:
-                o = self._canvas.get_component(u)["obj"].output(allow_partial=False)[1]
-                if o is not None:
-                    upstream_outs.append(o)
+            if self.component_name.lower().find("answer") >= 0 and self.get_component_name(u) in ["relevant"]:
+                continue
+            o = self._canvas.get_component(u)["obj"].output(allow_partial=False)[1]
+            if o is not None:
+                upstream_outs.append(o)
             break
 
         if upstream_outs:

api/apps/api_app.py

                 canvas.reference.append(final_ans["reference"])
             cvs.dsl = json.loads(str(canvas))
 
-            result = None
-            for ans in answer():
-                ans = {"answer": ans["content"], "reference": ans.get("reference", [])}
-                result = ans
-                fillin_conv(ans)
-                API4ConversationService.append_message(conv.id, conv.to_dict())
-                break
+            result = {"answer": final_ans["content"], "reference": final_ans.get("reference", [])}
+            fillin_conv(result)
+            API4ConversationService.append_message(conv.id, conv.to_dict())
             rename_field(result)
             return get_json_result(data=result)