chore(rds): modify the ACU limit for serverless v2 from 128 to 256

[mazyu36]

Issue # (if applicable)

N/A

Reason for this change

Currently, the ACU limit is 128 on CDK, but since it now supports up to 256.

Ref: Amazon Aurora Serverless v2 now supports up to 256 ACUs

Description of changes

Modify the ACU limit for serverless v2 from 128 to 256.

Description of how you validated changes

Modify unit tests and add an integ test.

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

[mazyu36]

Exemption Request: Since the ACU limit is not mentioned in the README, I think that no modification is necessary.

[aws-cdk-automation]

The pull request linter has failed. See the aws-cdk-automation comment below for failure reasons. If you believe this pull request should receive an exemption, please comment and provide a justification.

A comment requesting an exemption should contain the text Exemption Request. Additionally, if clarification is needed add Clarification Request to a comment.

[badmintoncryer]

LGTM!

[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: fc4401e
• Result: SUCCEEDED
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✅ Updated pull request passes all PRLinter validations. Dismissing previous PRLinter review.

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