remove service port name

Created by: xyz-li

What type of PR is this?

/kind documentation

What this PR does / why we need it:

remove service port name.

If the user sets the port name of service ks-apiserver. Then this cluster cannot be imported as a member cluster. Because the host ks-apiserver use the path /api/v1/namespaces/kubesphere-system/services/:ks-apiserver:/proxy/kapis/version to access the member ks-apiserver. As there is a port-name in the service ks-apiserver, the path must be /api/v1/namespaces/kubesphere-system/services/:ks-apiserver:ks-apiserver/proxy/kapis/version or /api/v1/namespaces/kubesphere-system/services/:ks-apiserver:80/proxy/kapis/version, the host cluster will get an error.

https://kubernetes.io/docs/tasks/access-application-cluster/access-cluster/#manually-constructing-apiserver-proxy-urls https://github.com/kubesphere/kubesphere/blob/master/pkg/kapis/cluster/v1alpha1/handler.go#L370

Which issue(s) this PR fixes:

Fixes #

Special notes for reviewers:

Does this PR introduced a user-facing change?

None

Additional documentation, usage docs, etc.: