Recalling the file uploaded while chatting. (#4472)

### What problem does this PR solve?

#4445

### Type of change

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

api/db/services/document_service.py

                     "kb_id": [kb.id],
                     "docnm_kwd": doc_nm[doc_id],
                     "title_tks": rag_tokenizer.tokenize(re.sub(r"\.[a-zA-Z]+$", "", doc_nm[doc_id])),
-                    "content_ltks": "",
+                    "content_ltks": rag_tokenizer.tokenize("summary summarize 总结 概况 file 文件 概括"),
                     "content_with_weight": mind_map,
                     "knowledge_graph_kwd": "mind_map"
                 })