Update Terraform AWS provider to 4.9+

What does this MR do?

MR upgrades the Terraform AWS provider to 4.9+.

The AWS team have retracted various breaking changes that had no straight upgrade path in this version after notable backlash that make it suitable for us to upgrade to from 3.74.x.

This is required to support #203 (closed), which is the replacement for AWS Elasticsearch service and has new Terraform resources (and the previous ones will very likely be deprecated which will cause problems in Terraform if we use those).

Related issues

Relates #203 (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: 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.