Allow setting cluster-dns-ip for Bottlerocket

[cPu1]

Description

Allows specifying multiple IPs as cluster DNS for Bottlerocket nodegroups by letting users specify cluster-dns-ip.

Closes #6834

Checklist

• Added tests that cover your change (if possible)
• Added/modified documentation as required (such as the README.md, or the userdocs directory)
• Manually tested
• Made sure the title of the PR is a good description that can go into the release notes
• (Core team) Added labels for change area (e.g. area/nodegroup) and kind (e.g. kind/improvement)

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 🌟