Fix: Handle the case of deleting empty blocks. Update the relevant message (#6643)

…gic to return the correct deletion message. Add handling for empty
arrays to ensure no errors occur during the deletion operation. Update
the test cases to verify the new logic.

### What problem does this PR solve?

fix this bug：https://github.com/infiniflow/ragflow/issues/6607

### Type of change

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

---------

Co-authored-by: wenju.li <wenju.li@deepctr.cn>

api/apps/sdk/doc.py

     if chunk_number != 0:
         DocumentService.decrement_chunk_num(document_id, dataset_id, 1, chunk_number, 0)
     if "chunk_ids" in req and chunk_number != len(unique_chunk_ids):
+        if len(unique_chunk_ids) == 0:
+            return get_result(message=f"deleted {chunk_number} chunks")
         return get_error_data_result(message=f"rm_chunk deleted chunks {chunk_number}, expect {len(unique_chunk_ids)}")
     if duplicate_messages:
         return get_result(message=f"Partially deleted {chunk_number} chunks with {len(duplicate_messages)} errors", data={"success_count": chunk_number, "errors": duplicate_messages},)

rag/utils/es_conn.py

             chunk_ids = condition["id"]
             if not isinstance(chunk_ids, list):
                 chunk_ids = [chunk_ids]
-            qry = Q("ids", values=chunk_ids)
+            if not chunk_ids:  # when chunk_ids is empty, delete all
+                qry = Q("match_all")
+            else:
+                qry = Q("ids", values=chunk_ids)
         else:
             qry = Q("bool")
             for k, v in condition.items():

sdk/python/test/test_http_api/test_chunk_management_within_dataset/test_delete_chunks.py

             ),
             (lambda r: {"chunk_ids": r[:1]}, 0, "", 4),
             (lambda r: {"chunk_ids": r}, 0, "", 1),
-            pytest.param({"chunk_ids": []}, 0, "", 0, marks=pytest.mark.skip(reason="issues/6607")),
+            pytest.param({"chunk_ids": []}, 0, "deleted 5 chunks", 0)
+
         ],
     )
     def test_basic_scenarios(