How should I proceed to the next step after running examples/python/t_reconstruction_system/run_system.py

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](https://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](https://www.open3d.org/docs/release/) and the [latest documentation](https://www.open3d.org/docs/latest/) (for `main` branch).

### My Question

After getting the fragments, how to merge the point cloud
```
python examples/python/t_reconstruction_system/run_system.py --split_fragments --fragment_odometry --fragment_integration --path_dataset /path/to/dataset