fix(rds): cannot use connections in rds.DatabaseInstance.fromLookup

[mazyu36]

Issue # (if applicable)

Closes #35192

Reason for this change

This change fixes an issue in DatabaseInstance.fromLookup() where port values aren't properly converted from strings to numbers.

This causes validation errors when setting up access permissions using the connections interface, as CfnSecurityGroupIngressProps requires port values to be numbers, not strings.

Description of changes

Modified instance.ts in the fromLookup method to convert the port string to a number.

Describe any new or updated permissions being added

N/A

Description of how you validated changes

Add a unit 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

[aws-cdk-automation]

(This review is outdated)

[mazyu36]

Exemption Request: The fix can be sufficiently validated with unit tests that verify port type conversion, and creating an integration test would require complex setup of dynamically referencing security group IDs between deployment stages.

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

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

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