make it work 1.12+ kube-apiserver --secure-port flag

[mengqiy]

Starting from 1.12, kube-apiserver not longer accept --secure-port=0.
So we should make it use a random port.

--secure-port int     Default: 6443
The port on which to serve HTTPS with authentication and authorization.It cannot be switched off with 0.

Ref: https://v1-12.docs.kubernetes.io/docs/reference/command-line-tools-reference/kube-apiserver/

[mengqiy]

/cc @apelisse

[apelisse]

That should be OK ...
/lgtm

[mengqiy]

Can someone approve it please?

[mengqiy]

@apelisse @hoegaarden

[apelisse]

/approve

[k8s-ci-robot]

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