chore(ec2): add c8gd, m8gd, and r8gd instance classes

[phuhung273]

Issue # (if applicable)

None

Reason for this change

https://aws.amazon.com/about-aws/whats-new/2025/04/amazon-ec2-c8gd-m8gd-r8gd-instances/

Description of how you validated changes

$ aws ec2 describe-instance-types | grep -e c8gd -e m8gd -e r8gd
            "InstanceType": "m8gd.metal-48xl",
            "InstanceType": "r8gd.xlarge",
            "InstanceType": "c8gd.48xlarge",
            "InstanceType": "c8gd.4xlarge",
            "InstanceType": "r8gd.8xlarge",
            "InstanceType": "c8gd.xlarge",
            "InstanceType": "c8gd.2xlarge",
            "InstanceType": "r8gd.medium",
            "InstanceType": "m8gd.8xlarge",
            "InstanceType": "c8gd.metal-48xl",
            "InstanceType": "c8gd.24xlarge",
            "InstanceType": "r8gd.16xlarge",
            "InstanceType": "m8gd.2xlarge",
            "InstanceType": "r8gd.4xlarge",
            "InstanceType": "c8gd.metal-24xl",
            "InstanceType": "r8gd.metal-24xl",
            "InstanceType": "m8gd.12xlarge",
            "InstanceType": "c8gd.medium",
            "InstanceType": "r8gd.large",
            "InstanceType": "m8gd.24xlarge",
            "InstanceType": "c8gd.8xlarge",
            "InstanceType": "m8gd.large",
            "InstanceType": "r8gd.24xlarge",
            "InstanceType": "m8gd.48xlarge",
            "InstanceType": "c8gd.12xlarge",
            "InstanceType": "m8gd.medium",
            "InstanceType": "r8gd.metal-48xl",
            "InstanceType": "m8gd.16xlarge",
            "InstanceType": "m8gd.xlarge",
            "InstanceType": "c8gd.16xlarge",
            "InstanceType": "c8gd.large",
            "InstanceType": "r8gd.12xlarge",
            "InstanceType": "m8gd.metal-24xl",
            "InstanceType": "r8gd.2xlarge",
            "InstanceType": "m8gd.4xlarge",
            "InstanceType": "r8gd.48xlarge",

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[aws-cdk-automation]

(This review is outdated)

[phuhung273]

Exemption Request: can be verified by CLI

✅ Updated pull request passes all PRLinter validations. Dismissing previous PRLinter review.

[paulhcsun]

@Mergifyio update

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: 910d001
• Result: SUCCEEDED
• Build Logs (available for 30 days)

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[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

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