CRASM-3171: Update RDS to use GP3 and higher IOPS

[aloftus23]

🗣 Description

Update storage_type to gp3 which allows us to configure iops independent of disk size. We are setting to 16,000 based on monitoring throughput during a data sync.

💭 Motivation and context

In testing the vulnScanningSync in parallel we hit major database roadblocks. Specifically, huge spikes in writeIops, readIops, and DisdkQueueDepth getting up to 40.

gp2 volume scales performance with storage so we only have about 3,000 IOPS. Need to increase with gp3

🧪 Testing

Passes pre-commit and github checks.

✅ Pre-approval checklist

• This PR has an informative and human-readable title.
• Changes are limited to a single goal - eschew scope creep!
• All future TODOs are captured in issues, which are referenced in code comments.
• All relevant type-of-change labels have been added.
• I have read the CONTRIBUTING document.
• These code changes follow cisagov code standards.
• All relevant repo and/or project documentation has been updated to reflect the changes in this PR.
• Tests have been added and/or modified to cover the changes in this PR.
• All new and existing tests pass.
• Bump major, minor, patch, pre-release, and/or build versions as appropriate via the bump_version script if this repository is versioned and the changes in this PR warrant a version bump.
• Create a pre-release (necessary if and only if the pre-release version was bumped).

✅ Pre-merge checklist

• Revert dependencies to default branches.
• Finalize version.

✅ Post-merge checklist

• Create a release (necessary if and only if the version was bumped).

[rapidray12]

We can do this after the upgrade to 17.6

[cduhn17]

LGTM - 1293

[rapidray12]

Now that the database has been upgraded to version 17.6 we can go ahead and appy this

[cduhn17]

@aloftus23 there is a new CRASM incoming to update the title of the PR