Replace annotations[scheduler.alpha.kubernetes.io/critical-pod] with priorityClassName: system-node-critical in ds.yml

[yeahdongcn]

The annotation is no longer working on recent versions of K8s, this PR replaces annotations[scheduler.alpha.kubernetes.io/critical-pod] with priorityClassName: system-node-critical in ds.yml.

$ kubectl apply -f daemonset.yml                                            
Warning: spec.template.metadata.annotations[scheduler.alpha.kubernetes.io/critical-pod]: non-functional in v1.16+; use the "priorityClassName" field instead
daemonset.apps/fake-device-plugin created
configmap/fake-device-plugin-cm created

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This change is