fix: Cannot set the IPv6 addresses in dualstack mode during modification

[wweiwei-li]

Issue

#3743

Description

• The issue occurs when changing the IP address Type to dualstack with a provided list of IPv6 addresses. The update is not being reflected because we only check if the subnets ID has changed.
• To support this, we should also check the IPv6 address. However, since IPv6 address can only be set once, we need to ensure it is being set for the first time. Additionally, we need to ensure this applies only to NLB

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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
• 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]

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