refactor: clean up API for removal policy across the library

[eladb]

• Normalize how deletion policy is configured for stateful resources across the AWS Construct Library. - Simplify the model by removing the future-proofing of "RemovalPolicy.Forbid".
• When RemovalPolicy.Destory is used, explicitly specify DeletionPolicy: Delete in CloudFormation (as oppose to relying on the fact the "Delete" is the default).

BREAKING CHANGE: multiple modules have been changed to use cdk.RemovalPolicy
to configure the resource's removal policy.

• core: applyRemovalPolicy is now CfnResource.applyRemovalPolicy.
• core: RemovalPolicy.Orphan has been renamed to Retain.
• core: RemovalPolicy.Forbid has been removed, use Retain.
• ecr: RepositoryProps.retain is now removalPolicy, and defaults to Retain instead of remove since ECR is a stateful resource
• kms: KeyProps.retain is now removalPolicy
• logs: LogGroupProps.retainLogGroup is now removalPolicy
• logs: LogStreamProps.retainLogStream is now removalPolicy
• rds: DatabaseClusterProps.deleteReplacePolicy is now removalPolicy
• rds: DatabaseInstanceNewProps.deleteReplacePolicy is now removalPolicy

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Pull Request Checklist

• Testing
  • Unit test added (prefer not to modify an existing test, otherwise, it's probably a breaking change)
  • CLI change?: coordinate update of integration tests with team
  • cdk-init template change?: coordinated update of integration tests with team
• Docs
  • jsdocs: All public APIs documented
  • README: README and/or documentation topic updated
  • Design: For significant features, design document added to design folder
• Title and Description
  • Change type: title prefixed with fix, feat and module name in parens, which will appear in changelog
  • Title: use lower-case and doesn't end with a period
  • Breaking?: last paragraph: "BREAKING CHANGE: <describe what changed + link for details>"
  • Issues: Indicate issues fixed via: "Fixes #xxx" or "Closes #xxx"
• Sensitive Modules (requires 2 PR approvers)
  • IAM Policy Document (in @aws-cdk/aws-iam)
  • EC2 Security Groups and ACLs (in @aws-cdk/aws-ec2)
  • Grant APIs (only if not based on official documentation with a reference)

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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.

[rix0rrr]

When RemovalPolicy.Destory is used, explicitly specify DeletionPolicy: Delete in CloudFormation (as oppose to relying on the fact the "Delete" is the default).

Why?

[rix0rrr]

I suppose it's good that you're doing a bit-for-bit replacement of functionality, but I actually think it's a bug if this is ever set to false. We should always treat updates the same as deletes (because they will be physical deletes).

[eladb]

I was just unsure whether applying this everywhere will break something and felt it's not the right thing to spend my time on.

[rix0rrr]

Alright then: #2901

[eladb]

When RemovalPolicy.Destory is used, explicitly specify DeletionPolicy: Delete in CloudFormation (as oppose to relying on the fact the "Delete" is the default).

I think it's a better practice to be explicit about deletion of stateful resources.

[rix0rrr]

I think it's a better practice to be explicit about deletion of stateful resources.

You're being explicit about it in a place where no-one should ever or is ever going to look, and even if they were the semantics are well-defined and well-understood. I don't really see the point. But if it makes you happy, not a big deal.

[mergify]

Thanks so much for taking the time to contribute to the AWS CDK ❤️

We will shortly assign someone to review this pull request and help get it
merged. In the meantime, please take a minute to make sure you follow this
checklist:

• PR title type(scope): text
  • type: fix, feat, refactor go into CHANGELOG, chore is hidden
  • scope: name of module without aws- or cdk- prefix or postfix (e.g. s3 instead of aws-s3-deployment)
  • text: use all lower-case, do not end with a period, do not include issue refs
• PR Description
  • Rationale: describe rationale of change and approach taken
  • Issues: indicate issues fixed via: fixes #xxx or closes #xxx
  • Breaking?: last paragraph: BREAKING CHANGE: <describe what changed + link for details>
• Testing
  • Unit test added. Prefer to add a new test rather than modify existing tests
  • CLI or init templates change? Re-run/add CLI integration tests
• Documentation
  • README: update module README to describe new features
  • API docs: public APIs must be documented. Copy from official AWS docs when possible
  • Design: for significant features, follow design process