Test: update test cases per pr #6095 to fix issue #6039 (#6143)

### What problem does this PR solve?

update test case per pr #6095 to fix issue #6039

### Type of change

- [x] update test case

sdk/python/test/test_http_api/test_file_management_within_dataset/test_upload_documents.py

@@ -140,9 +140,7 @@ class TestUploadDocuments:
         fp = create_txt_file(tmp_path / f"{'a' * (DOCUMENT_NAME_LIMIT - 3)}.txt")
         res = upload_documnets(get_http_api_auth, ids[0], [fp])
         assert res["code"] == 101
-        assert (
-            res["message"].find("128") >= 0
-        )
+        assert res["message"] == "File name should be less than 128 bytes."
 
     def test_invalid_dataset_id(self, get_http_api_auth, tmp_path):
         fp = create_txt_file(tmp_path / "ragflow_test.txt")
@@ -206,7 +204,6 @@ class TestUploadDocuments:
         res = list_dataset(get_http_api_auth, {"id": ids[0]})
         assert res["data"][0]["document_count"] == expected_document_count
 
-    @pytest.mark.xfail
     def test_concurrent_upload(self, get_http_api_auth, tmp_path):
         ids = create_datasets(get_http_api_auth, 1)