enable S3 Bucket key by default

[perzycharles]

What does this PR do?

enable S3 bucket key by default to decrease KMS cost.
https://docs.aws.amazon.com/AmazonS3/latest/userguide/bucket-key.html
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-s3-bucket-serversideencryptionrule.html#aws-properties-s3-bucket-serversideencryptionrule-properties

Motivation

CLOUDS-5426 and slack

Testing Guidelines

Additional Notes

Types of changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog
• This PR passes the integration tests (ask a Datadog member to run the tests)
• This PR passes the unit tests
• This PR passes the installation tests (ask a Datadog member to run the tests)

[ge0Aja]

lgtm