fix: Resolve instability with SG for Pods lab cleanup

[niallthomson]

What this PR does / why we need it:

User reports and automated tests show instability in the SG for Pods lab cleanup script. This seems to be related to a wide variability in how long it takes the worker nodes to be replaced when they are terminated in cleanup.

This change removes the node termination and instead deletes the catalog namespace, which should clean up all modifications made during this lab.

Which issue(s) this PR fixes:

Related to #1062

Quality checks

• My content adheres to the style guidelines
• I ran make test module="<module>" it was successful (see https://github.com/aws-samples/eks-workshop-v2/blob/main/docs/automated_tests.md)

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[netlify]

✅ Deploy Preview for eks-workshop ready!

Name	Link
🔨 Latest commit	f161993
🔍 Latest deploy log	https://app.netlify.com/sites/eks-workshop/deploys/66f7526c046e390008687341
😎 Deploy Preview	https://deploy-preview-1117--eks-workshop.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.