ClusterLoader：need to suport get etcd mtrics by cert file

[keontang]

I have a v1.11.2 k8s cluster with an etcd cluster which enables auth by cert file.
When i run clusterloader2, EtcdMetrics measurement failed to get etcd metrics by http:

perf-tests/clusterloader2/pkg/measurement/common/etcd_metrics.go

Line 100 in f7ae863

cmd := "curl http://localhost:2379/metrics"

func getEtcdMetrics(provider, host string) ([]*model.Sample, error) {

	...
       cmd := "curl http://localhost:2379/metrics"
	...

}

so, i think maybe we need to suport get etcd mtrics by cert file.

[fejta-bot]

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[wojtek-t]

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[wojtek-t]

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[WangEP]

If you use kubeadm to build the cluster, the metric port may not 2379. In my machine, it's 2381. you can use “ps aux | grep -P '/etc[d] ' ” to get in detail( pay attention to the “--listen-metrics-urls=”)