fix: handle comma-separated provided IPs

[mainred]

What type of PR is this?

/kind bug
For dual-stack Windows case, both ipv4 and ipv6 ip address are provided and separated by comma in a string. This change is to split the ipv4 and ipv6 addresses and check whether all these provided IPs exist in the cloud provider.

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

For dual-stack Windows case, both ipv4 and ipv6 ip address are provided and separated by comma in a string. This change is to split the ipv4 and ipv6 addresses and check whether all these provided IPs exist in the cloud provider.

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

Hi @mainred. 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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[MartinForReal]

/kind bug

[MartinForReal]

Could you please update the release note?

[MartinForReal]

/ok-to-test

[mainred]

/test pull-cloud-provider-azure-e2e-ccm-vmssflex-capz

[feiskyer]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: feiskyer, mainred

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[lzhecheng]

/retest

[feiskyer]

/cherry-pick release-1.29

[k8s-infra-cherrypick-robot]

@feiskyer: new pull request created: #5759

In response to this:

/cherry-pick release-1.29

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.