disable automatic NVIDIA driver upgrades

Automatic upgrades of the NVIDIA driver are dangerous in production
given that they often happen unattended and are likely to cause issues
on at least a subset of nodes. In the best case, user workloads are
impacted at unpredictable times.

This patch disables automatic upgrades by default. Systems that want
automatic upgrades should patch the GPU cluster policy in an overlay.

nvidia-gpu-operator/base/gpu-cluster-policy.yaml

@@ -38,7 +38,7 @@ spec:
     repoConfig:
       configMapName: ""
     upgradePolicy:
-      autoUpgrade: true
+      autoUpgrade: false
       drain:
         deleteEmptyDir: false
         enable: false