[GraphBolt][Bug] SEGV when preprocessing `OnDiskDataset`

## 🐛 Bug

## To Reproduce

When trying to construct a `OnDiskDataset` with the UK-Union graph, I get segmentation fault during preprocessing. The error message is either `munmap_chunk(): invalid pointer` or `double free or corruption (out)`. I further locate the error comes from the following line:

https://github.com/dmlc/dgl/blob/1547bd931d17cd1da144a6d38bb687c0f2c3b364/python/dgl/graphbolt/impl/ondisk_dataset.py#L97

Steps to reproduce the behavior:

execute the code:

```python
import dgl.graphbolt as gb
dataset = gb.OnDiskDataset("path/to/dataset")
```

## Expected behavior

## Environment

- DGL Version (e.g., 1.0): 2.1.0+cu121
- Backend Library & Version (e.g., PyTorch 0.4.1, MXNet/Gluon 1.3): PyTorch 2.1.2+cu121
- OS (e.g., Linux): Linux
- How you installed DGL (`conda`, `pip`, source): pip
- Build command you used (if compiling from source):
- Python version: 3.11
- CUDA/cuDNN version (if applicable):
- GPU models and configuration (e.g. V100):
- Any other relevant information:

## Additional context