Update Istio to 1.5.4

Author: github-actions[bot]

istio/operator/manifests.yaml

@@ -224,7 +224,7 @@ spec:
       serviceAccountName: istio-operator
       containers:
         - name: istio-operator
-          image: docker.io/istio/operator:1.5.3
+          image: docker.io/istio/operator:1.5.4
           command:
           - operator
           - server