[Bug] 对已有图执行克隆后，查询克隆图的schema和数据全部为空。

### Bug Type (问题类型)

rest-api (结果不合预期)

### Before submit

- [X] 我已经确认现有的 [Issues](https://github.com/apache/hugegraph/issues) 与 [FAQ](https://hugegraph.apache.org/docs/guides/faq/) 中没有相同 / 重复问题 (I have confirmed and searched that there are no similar problems in the historical issue and documents)

### Environment (环境信息)

- Server Version: 0.12.0
- Backend: RocksDB

### Expected & Actual behavior (期望与实际表现)

对已有图执行clone操作后，对新的clone图执行查询，所有数据均为空。测试了rocksdb和cassandra/scylladb等三种后端

### Vertex/Edge example (问题点 / 边数据举例)

_No response_

### Schema [VertexLabel, EdgeLabel, IndexLabel] (元数据结构)

_No response_

Start with the REST API clone operation and reproduce the issue on HugeGraph Server 0.12.0 using the reported RocksDB backend. Compare schema and data queries on the original and cloned graphs, then verify the clone preserves both across the reported backends.

Written by the indexing model from the issue text.