Update select NGinx settings such as selector for AWS CNH LB

What does this MR do?

MR adds additional config for AWS Cloud Native Hybrid Load Balancer as configured by Helm as follows:

• NGinx nodes now deploy to the Support node pool again as expected
• AWS LB Target Pools now only target the Support node pool to stop giving false negatives
• Cross Load Balancing config has been updated to the correct format that works (a new format is coming in but this doesn't appear to be active on AWS yet)
• Added a new setting for AWS Created network to exclude an AZ when it doesn't have the resources required.

Related issues

Closes https://gitlab.com/gitlab-org/quality/gitlab-environment-toolkit/-/issues/347

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
• 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: setup 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.