Spherical transformation error

### 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

Hey,

within the following examle:

https://github.com/isl-org/Open3D/blob/9238339b99afea902fb2e4a5c614699fd97f6b02/examples/python/geometry/voxel_grid_carving.py#L12

the calculation seems to be wrong. The angle calculation is:
```
r_x = np.arccos(y / r)
r_y = np.arctan2(z, x)
```
But shouldn't it be:
```
r_x = np.arccos(z / r)
r_y = np.arctan2(y, x)
```

Or am I missing something?

### Steps to reproduce the bug

```python
Calculation is wrong.
```

### Error message

_No response_

### Expected behavior

_No response_

### Open3D, Python and System information

```markdown
- Operating system: Ubuntu 20.04
- Python version: Python 3.8
- Open3D version: 0.15.2
- System architecture: x86
- Is this a remote workstation?: yes
- How did you install Open3D?: build from source
- Compiler version (if built from source): gcc 9.4
```

### Additional information

_No response_