Fix Github workflow for updating generated files for default addons

[TiberiuGC]

Description

The Github workflow responsible for upgrading the manifests for default aws-node and coredns addons has been broken for a while.
https://github.com/eksctl-io/eksctl/actions/workflows/update-generated.yaml

This PR aims to provide a fix for that. People have been experiencing issues with eksctl utils update commands since the generated files were out of date for long period of time. e.g. #7755

Additionally, the PR includes a fix for the update coredns PR, as in, it excludes preview versions when trying to resolve the latest. Manual test for that #7767

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 🌟