Remove experimental note for ipvs in kube-proxy arguments

[johscheuer]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind api-change
/kind bug

/kind cleanup

/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake

What this PR does / why we need it:
This PR removes the experimental note for the kube-proxy mode ipvs. ipvs is since 1.11 GA see:
https://kubernetes.io/blog/2018/07/09/ipvs-based-in-cluster-load-balancing-deep-dive/ and #58442. The experimental note is confusing for people that are new to Kubernetes.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[k8s-ci-robot]

Hi @johscheuer. Thanks for your PR.

I'm waiting for a kubernetes 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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[johscheuer]

/sig network

[vllry]

/approve

[vllry]

/assign @johnbelamaric

[johnbelamaric]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: johnbelamaric, johscheuer, vllry

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