feat: drop `nvidia-cdi-hook` shell shim

This PR drops the `nvidia-cdi-hook` shell shim that exec's `nvidia-cdi-hook.real`,
the shim was not doing anything extra in this case as like the legacy shims.

This allows using toolkit installation on hosts that don't have a shell
at all, when using NRI mode runc exec's `nvidia-cdi-hook`.

This is part of fixing upstream discussion at https://github.com/NVIDIA/gpu-operator/discussions/2385

Signed-off-by: Noel Georgi <git@frezbo.dev>