make fluentd a critical pod

Signed-off-by: Vishnu kannan <vishnuk@google.com>

cluster/addons/fluentd-gcp/fluentd-gcp-ds.yaml

@@ -15,6 +15,11 @@ spec:
         k8s-app: fluentd-gcp
         kubernetes.io/cluster-service: "true"
         version: v1.35
+  # This annotation ensures that fluentd does not get evicted if the node
+  # supports critical pod annotation based priority scheme.
+  # Note that this does not guarantee admission on the nodes (#40573).
+      annotations:
+        scheduler.alpha.kubernetes.io/critical-pod: ''
     spec:
       containers:
       - name: fluentd-gcp