Install selector doesn't need NVIDIA index for cuVS

[bdice]

Currently, selecting cuVS with pip adds the NVIDIA package index. This isn't required anymore.

We should audit the list of which packages require the NVIDIA package index. I think it's just cuGraph, but maybe @jameslamb knows where this list can be found.

[jameslamb]

We should audit the list of which packages require the NVIDIA package index. I think it's just cuGraph, but maybe @jameslamb knows where this list can be found.

• cuGraph and anything depending on it (e.g. cugraph-pyg, nx-cugraph)
• cuOpt family of packages

This is tracked at https://github.com/rapidsai/build-infra/issues/349 (private issue, sorry)