chore(doc): update service healthcheck timeout documentation

[phuhung273]

Issue

Closes #3838

Description

• Doc: remove outdated note that service.beta.kubernetes.io/aws-load-balancer-healthcheck-timeout is ignored

Checklist

• Added tests that cover your change (if possible)
• Added/modified documentation as required (such as the README.md, or the docs directory)
• Manually tested
• Confirm LBC able to modify Target Group healthcheck timeout when service annotation updated
• Local doc preview

• Made sure the title of the PR is a good description that can go into the release notes

BONUS POINTS checklist: complete for good vibes and maybe prizes?! 🤯

• Backfilled missing tests for code in same general area 🎉
• Refactored something and made the world a better place 🌟

[k8s-ci-robot]

Hi @phuhung273. 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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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: phuhung273
Once this PR has been reviewed and has the lgtm label, please assign oliviassss for approval. For more information see the Kubernetes Code Review Process.

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