Removing and readding a PointCloud geometry with the same name to O3DVisualizer leads to it disappearing when rotating the camera

### 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](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### Describe the issue

Removing and readding a PointCloud geometry with the same name to O3DVisualizer leads to it disappearing when rotating the camera. The terminal displays the warning;
`[Open3D WARNING] Geometry point_cloud.__fast__ is not in the scene graph`

Manually deleting "point_cloud.__fast__" from the scene fixes the problem, however the downsampled point cloud is no longer used when moving the camera.

### Steps to reproduce the bug

```python
sw = o3d.visualization.gui.SceneWidget() # scene widget
sw.scene = o3d.visualization.rendering.Open3DScene(window.renderer)
pcd = PointCloud() # some point cloud
...
sw.scene.add_geometry("point_cloud", pcd, material)
...
sw.scene.remove_geometry("point_cloud")
sw.scene.add_geometry("point_cloud", pcd, material)
```

### Error message

_No response_

### Expected behavior

_No response_

### Open3D, Python and System information

```markdown
- Operating system: Ubuntu 20.04 / macOS 10.15 / Windows 10 64-bit
- Python version: Python 3.8 / output from `import sys; print(sys.version)`
- Open3D version: output from python: `print(open3d.__version__)`
- System architecture: x86 / arm64 / apple-silicon / jetson / rpi
- Is this a remote workstation?: yes or no
- How did you install Open3D?: pip / conda / build from source
- Compiler version (if built from source): gcc 7.5 / clang 7.0
```

### Additional information

_No response_