remove replicate set fallback behavior (#12865)

replica set deployment style is an incorrect
style of distributed MinIO deployment, since
statefulsets have been around for many releases
in k8s now.

cmd/update.go

@@ -150,11 +150,6 @@ func IsDCOS() bool {
 	return false
 }
 
-// IsKubernetesReplicaSet returns true if minio is running in kubernetes replica set.
-func IsKubernetesReplicaSet() bool {
-	return IsKubernetes() && (env.Get("KUBERNETES_REPLICA_SET", "") != "")
-}
-
 // IsKubernetes returns true if minio is running in kubernetes.
 func IsKubernetes() bool {
 	if env.Get("MINIO_CI_CD", "") == "" {