feat(rds): support Database Insights for Aurora databases (#32851)

### Issue # (if applicable)

Closes #32680

### Reason for this change
AWS announces Amazon CloudWatch Database Insights.
https://aws.amazon.com/about-aws/whats-new/2024/12/amazon-cloudwatch-database-insights

### Description of changes
Database Insights has two modes: Standard and Advanced.
For Aurora databases, standard mode is enabled by default.
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-rds-dbcluster.html#aws-resource-rds-dbcluster-return-values

When using advanced mode, you must enable Performance Insights and set its data retention period to 465 days.
https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/Database-Insights.html

### Describe any new or updated permissions being added
Nothing.

### Description of how you validated changes
Unit tests and integ-tests.

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

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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*