fix(codepipeline): clean up cross-region replication buckets

[nanookclaw]

Issue # (if applicable)

Closes #35654.

Reason for this change

CodePipeline cross-region support stacks currently retain their replication bucket by default, which can leave an orphaned bucket after destroying the pipeline stack. Because changing the default removal policy could be disruptive for existing deployments, this adds the cleanup behavior behind an opt-in feature flag.

Description of changes

• Adds @aws-cdk/aws-codepipeline:crossRegionReplicationBucketDestroy as a recommended feature flag.
• When the flag is enabled, cross-region replication buckets are created with RemovalPolicy.DESTROY and autoDeleteObjects: true.
• Keeps existing retain behavior when the flag is unset/disabled.
• Adds coverage for both legacy retain behavior and the feature-flag-enabled cleanup behavior.

Description of how you validated changes

• PATH=/tmp/yarn-bin:$PATH npx lerna run build --scope aws-cdk-lib --skip-nx-cache --stream
• cd packages/aws-cdk-lib && node ../../node_modules/jest/bin/jest.js --config jest.config.js cx-api/test/features.test.ts aws-codepipeline/test/cross-env.test.ts --runInBand --coverage=false
• cd packages/aws-cdk-lib && NODE_OPTIONS='--max-old-space-size=8192' ../../node_modules/.bin/eslint aws-codepipeline/lib/private/cross-region-support-stack.ts aws-codepipeline/test/cross-env.test.ts cx-api/lib/features.ts cx-api/test/features.test.ts

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]

(This review is outdated)

[nanookclaw]

Added the integration-test coverage requested by the PR linter in 89c8f6901f.

The follow-up enables @aws-cdk/aws-codepipeline:crossRegionReplicationBucketDestroy in the existing dry-run cross-region CodePipeline integ (integ.codepipeline-with-nested-stack) and updates the committed snapshot. The snapshot now shows the generated cross-region replication bucket moving to DeletionPolicy: Delete / UpdateReplacePolicy: Delete with the Custom::S3AutoDeleteObjects resources present.

Verification run after the snapshot update:

• PATH=/tmp/yarn-bin:$PATH NODE_OPTIONS='--max-old-space-size=8192' npx lerna run build --scope aws-cdk-lib --skip-nx-cache --stream
• cd packages/aws-cdk-lib && NODE_OPTIONS='--max-old-space-size=8192' ../../node_modules/jest/bin/jest.js --config jest.config.js cx-api/test/features.test.ts aws-codepipeline/test/cross-env.test.ts --runInBand --coverage=false
• cd packages/aws-cdk-lib && NODE_OPTIONS='--max-old-space-size=8192' ../../node_modules/.bin/eslint aws-codepipeline/lib/private/cross-region-support-stack.ts aws-codepipeline/test/cross-env.test.ts cx-api/lib/features.ts cx-api/test/features.test.ts
• cd packages/@aws-cdk-testing/framework-integ && PATH=/tmp/yarn-bin:$PATH NODE_OPTIONS='--max-old-space-size=8192' yarn build
• cd packages/@aws-cdk-testing/framework-integ && PATH=/tmp/yarn-bin:$PATH NODE_OPTIONS='--max-old-space-size=8192' yarn integ aws-codepipeline-actions/test/integ.codepipeline-with-nested-stack --update-on-failed --dry-run

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