Handle AWS service disk type and iops dependency better

What does this MR do?

MR adds more graceful handling for AWS service (RDS and OpenSearch) disk iops settings.

The default disk type we use, io1, requires that an iops setting is passed as well but a newer alternative, gp3, is now available that doesn't want that setting set (and optionally allows it only when the disk size is 400gb or higher). MR adds some handling for this when users create new services with gp3.

It's worth noting as part of this work an upstream bug was discovered that prevents a straight conversation of types like this (even though it should be possible) but this will allow users to deploy with gp3 for new environments at least.

Related issues

Closes #765 (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.