[release-1.1] fix: should update dns label if target pip already have one and it needs update

[k8s-infra-cherrypick-robot]

This is an automated cherry-pick of #2665

/assign MartinForReal

Fix an issue when DNS label of public ip is not updated when service.beta.kubernetes.io/azure-dns-label-name is changed.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: k8s-infra-cherrypick-robot
Once this PR has been reviewed and has the lgtm label, please assign nilo19 for approval by writing /assign @nilo19 in a comment. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[k8s-ci-robot]

@k8s-infra-cherrypick-robot: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cloud-provider-azure-unit-1-22	aa74803	link	true	/test pull-cloud-provider-azure-unit-1-22
pull-cloud-provider-azure-e2e-ccm-vmss-capz-1-22	aa74803	link	true	/test pull-cloud-provider-azure-e2e-ccm-vmss-capz-1-22
pull-cloud-provider-azure-e2e-ccm-capz-1-22	aa74803	link	true	/test pull-cloud-provider-azure-e2e-ccm-capz-1-22

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[k8s-triage-robot]

Unknown CLA label state. Rechecking for CLA labels.

Send feedback to sig-contributor-experience at kubernetes/community.

/check-cla
/easycla