Schedule pods on a nodegroup on which no concurrent actions are executed

[TiberiuGC]

Description

Fixes #7792

CRUD integration test creates a bunch of nodegroups, on which, some of the specs, then execute different operations e.g. scale, delete, etc. Other parallel specs apply daemonsets, deployments, etc. Depending on timing, one spec might delete and/or drain a node onto which pods were scheduled by another spec, right when the namespace in which the pods are running is being terminated.

To fix ☝🏻, this PR ensures that all pods are scheduled on a separate nodegroup, onto which no other concurrent action is being executed.

Manual testing

https://github.com/eksctl-io/eksctl-ci/actions/runs/9510689795/job/26218234718

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 🌟