feat(events-targets): prevent to create a log group resource policy

[Tietew]

Issue # (if applicable)

Closes #31404.

Reason for this change

A CloudWatch LogGroup target creates a custom resource to create a LogGroup Resource Policy to permit EventBridge to put log events to the LogGroup. However, there is a strict quota of 10 Resource Policies per account per region. This therefore limits the amount of EventBridge rules targetting to CloudWatch Logs.

Description of changes

An optional prop createLogGroupResourcePolicy has been added to the LogGroupProps. When set to false, creation of LogGroup Resource Policy will be omitted. The default value is true to keep current behavior.

Setting createLogGroupResoucePolicy to false needs user to create a LogGroup Resouce Policy separately. See README for details.

Describe any new or updated permissions being added

N/A

Description of how you validated changes

Added unit tests:

• assert the custom resource is created by default
• assert the custom resource is absent when the createLogGroupResourcePolicy is false.

Added a event rule with createLogGroupResourcePolicy set to false to the existing 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