fix get port used

[ikaven1024]

What type of PR is this?

/kind bug

What this PR does / why we need it:

When I create two clusters on my side：

kwokctl create cluster --runtime=binary --kube-apiserver-binary ~/bin/kube-apiserver --kube-controller-manager-binary ~/bin/kube-controller-manager --kube-scheduler-binary ~/bin/kube-scheduler --kwok-controller-binary /opt/homebrew/bin/kwok --etcd-binary ~/bin/etcd --name cluster1
kwokctl create cluster --runtime=binary --kube-apiserver-binary ~/bin/kube-apiserver --kube-controller-manager-binary ~/bin/kube-controller-manager --kube-scheduler-binary ~/bin/kube-scheduler --kwok-controller-binary /opt/homebrew/bin/kwok --etcd-binary ~/bin/etcd --name cluster2

I found etcds in both cluster are using 32766 port.

Etcd is listening on 'localhost:32766', while I run below code returns no error:

listener, err = net.Listen("tcp", ":32766")

So I change the UnusedPort function in this PR to fix this problem.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: ikaven1024 / name: yjh (8c1beca)

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[k8s-ci-robot]

Hi @ikaven1024. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[wzshiming]

/ok-to-test

[wzshiming]

/approve
/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ikaven1024, wzshiming

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