aws-elb: allow manipulating all attributes

### Describe the feature

Some attributes like `ConnectionDraining` cannot be setup via API.
It is only available via CLI or web UI.
This is hindering IaC tools and the Kubernetes operator.

Reference:
https://docs.aws.amazon.com/elasticloadbalancing/latest/APIReference/API_LoadBalancerAttribute.html

### Use Case

I want to setup (enable/disable or modify the timeout) the "connection draining" attribute of my LBs via IaC or K8s.

### Proposed Solution

Add that existing feature to API.

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### AWS CDK Library version (aws-cdk-lib)

aws-cdk-lib@2.198.0

### AWS CDK CLI version

aws-cli/2.27.22 Python/3.13.3 Darwin/24.5.0 source/arm64

### Environment details (OS name and version, etc.)

macOS 15.5 Sequoia

Start with the AWS LoadBalancerAttribute API reference linked in the issue and locate the aws-elasticloadbalancing implementation that exposes load balancer attributes. Confirm how ConnectionDraining and the remaining attributes should be represented and tested; done means IaC and Kubernetes users can enable, disable, or modify the connection-draining timeout through the API.

Written by the indexing model from the issue text.