Draft: Switch to separate node roles for AWS EKS

What does this MR do?

As a reachable best practice it's sensible to have separate IAM roles for the AWS EKS Node Groups. This allows us to separate permissions for pods to only apply on the nodes that run them.

MR does just this along with some general cleanup and following AWS latest recommendations.

Note: This is a disruptive change, the switching of a node group role requires recreation in AWS so this will result in downtime on upgrade (around 12 mins when I tested it).

Related issues

Closes #656 (closed)

Author's checklist

When ready for review, the Author applies the workflowready for review label and mention @gl-quality/get-maintainers:

• Merge request:
  • Corresponding Issue raised and reviewed by the GET maintainers team.
  • Merge Request Title and Description are up-to-date, accurate, and descriptive
  • MR targeting the appropriate branch
  • MR has a green pipeline
  • MR has no new security alerts in the widget from the Secret Detection and IaC Scan (SAST) jobs.
• Code:
  • Check the area changed works as expected. Consider testing it in different environment sizes (1k,3k,10k,etc.).
  • Documentation created/updated in the same MR.
  • If this MR adds an optional configuration - check that all permutations continue to work.
  • For Terraform changes: set up a previous version environment, then run a terraform plan with your new changes and ensure nothing will be destroyed. If anything will be destroyed and this can't be avoided please add a comment to the current MR.
• Create any follow-up issue(s) to support the new feature across other supported cloud providers or advanced configurations. Create 1 issue for each provider/configuration. Contact the Quality Enablement team if unsure.