devel packages are no longer released for linux

### 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).

### Steps to reproduce the issue

- [release page for devel packages](https://github.com/isl-org/Open3D/releases/tag/main-devel) has no longer linux packages (only win and macosx)
- links for python packages on https://www.open3d.org/docs/latest/getting_started.html are broken

### Error message

```shell
404 error!

for instance, today's open3d-cpu for py3.12 links to a 404 https://github.com/isl-org/Open3D/releases/download/main-devel/open3d_cpu-0.18.0+81201f9-cp312-cp312-manylinux_2_31_x86_64.whl
```

### Open3D, Python and System information

```markdown
N/A (but interested by open3d-cpu on linux for py3.12 for which only the devel version is available)
```

### Additional information

_No response_