fix(opensearchservice): added r7gd instance

[khushail]

Issue # (if applicable)

Closes #32138

Reason for this change

The instance r7gd does not use EBS Storage, so it needed to be added to list of instances

Description of changes

Updated the list of instances that does not need EBS Storage

Description of how you validated changes

adding integration and unit tests

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

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

[aws-cdk-automation]

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[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: 190190a
• Result: FAILED
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[aws-cdk-automation]

This PR has been in the CHANGES REQUESTED state for 3 weeks, and looks abandoned. To keep this PR from being closed, please continue work on it. If not, it will automatically be closed in a week.

[khushail]

wil add test snapshot soon

[aws-cdk-automation]

This PR has been deemed to be abandoned, and will be automatically closed. Please create a new PR for these changes if you think this decision has been made in error.

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[aws-cdk-automation]

The pull request linter fails with the following errors:

❌ Fixes must contain a change to an integration test file and the resulting snapshot.

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