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 🌟

[shraddhabang]

/lgtm
/approve

[shraddhabang]

/lgtm

[k8s-ci-robot]

New changes are detected. LGTM label has been removed.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: shraddhabang, wweiwei-li, zac-nixon

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 70.58824% with 5 lines in your changes missing coverage. Please review.

Project coverage is 49.94%. Comparing base (e5d625f) to head (643f33d).
Report is 62 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/deploy/elbv2/load_balancer_manager.go	70.58%	2 Missing and 3 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #3959       +/-   ##
===========================================
+ Coverage   18.20%   49.94%   +31.74%     
===========================================
  Files         175      205       +30     
  Lines       29280    12115    -17165     
===========================================
+ Hits         5330     6051      +721     
+ Misses      23584     5648    -17936     
- Partials      366      416       +50     

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