func SetCluster(name string, fcn func() cluster.Cluster) {
	clusters[name] = fcn
}
SetCluster sets the cluster fault-tolerant mode with @name
For example: available/failfast/broadcast/failfast/failsafe/...
package extension
import (
	"dubbo.apache.org/dubbo-go/v3/cluster"
)
var clusters = make(map[string]func() cluster.Cluster)