Fix: change create dataset htto api delimiter default value to r'\n' (#7434)

### What problem does this PR solve?

change create dataset delimiter default value to r'\n'

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

sdk/python/test/test_http_api/test_dataset_mangement/test_create_dataset.py

@@ -400,7 +400,7 @@ class TestDatasetCreation:
         if parser_config is None:
             assert res["data"]["parser_config"] == {
                 "chunk_token_num": 128,
-                "delimiter": r"\n!?;。；！？",
+                "delimiter": r"\n",
                 "html4excel": False,
                 "layout_recognize": "DeepDOC",
                 "raptor": {"use_raptor": False},
@@ -410,7 +410,7 @@ class TestDatasetCreation:
                 "auto_keywords": 0,
                 "auto_questions": 0,
                 "chunk_token_num": 128,
-                "delimiter": r"\n!?;。；！？",
+                "delimiter": r"\n",
                 "filename_embd_weight": None,
                 "graphrag": None,
                 "html4excel": False,

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

@@ -303,7 +303,7 @@ class TestUpdateDocumentParserConfig:
                     "chunk_token_num": 128,
                     "layout_recognize": "DeepDOC",
                     "html4excel": False,
-                    "delimiter": "\\n!?;。；！？",
+                    "delimiter": r"\n",
                     "task_page_size": 12,
                     "raptor": {"use_raptor": False},
                 },
@@ -530,7 +530,7 @@ class TestUpdateDocumentParserConfig:
             else:
                 assert res["data"]["docs"][0]["parser_config"] == {
                     "chunk_token_num": 128,
-                    "delimiter": "\\n!?;。；！？",
+                    "delimiter": r"\n",
                     "html4excel": False,
                     "layout_recognize": "DeepDOC",
                     "raptor": {"use_raptor": False},