Allow CDI hooks to be disabled

[cdesiniotis]

Testing

$ grep "ModifyDeviceFile" /proc/driver/nvidia/params
ModifyDeviceFiles: 1

$ cat pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: gpu-sleep
spec:
  restartPolicy: Never
  containers:
    - name: main
      image: ubuntu
      command: ["sh", "-c", "sleep infinity"]
      resources:
        limits:
          nvidia.com/gpu: 1

$ kubectl apply -f pod.yaml
pod/gpu-sleep created

$ kubectl exec -it gpu-sleep -- grep "ModifyDeviceFile" /proc/driver/nvidia/params
ModifyDeviceFiles: 0

$ kubectl delete -f pod.yaml
pod "gpu-sleep" deleted from default namespace

// add below env to device-plugin daemonset
// env:
// - name: CDI_DISABLE_HOOKS
     value: "disable-device-node-modification, update-ldcache"

// after plugin restarts, observe that boths hooks are omitted from the generated CDI spec

$ kubectl apply -f pod.yaml
pod/gpu-sleep created

$ kubectl exec -it gpu-sleep -- grep "ModifyDeviceFile" /proc/driver/nvidia/params
ModifyDeviceFiles: 1

[cdesiniotis]

I updated the description of the cdi-disabled-hooks flag to also include:

The special hook name 'all' can be used to ensure the generated CDI specification does not include any hooks.

[LandonTClipp]

Thank you @cdesiniotis!