fix kube-override-hostname, support purely numeric

[KubeKyrie]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #10987

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

fix kube-override-hostname not supporting purely numbers

[k8s-ci-robot]

Hi @KubeKyrie. Thanks for your PR.

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: KubeKyrie
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[KubeKyrie]

Test results:

hostname is set 666 and cluster can be created successfully.
ansible-playbook -i inventory/mycluster/hosts.yaml --become --become-user=root cluster.yml -e unsafe_show_logs=true -vv

[yankay]

/ok-to-test

[KubeKyrie]

Seems #10997 fixed, close