feat(ecs): support availability zone rebalancing (#32263)

### Issue # (if applicable)

Closes #32226

### Reason for this change

New AZ rebalancing feature is not yet supported in L2 constructs.


### Description of changes

Add `availabilityZoneRebalancing` to the props of FargateService and Ec2Service, and validate all the documented constraints on it being `ENABLED`.


### Description of how you validated changes

Unit and integration 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*

Author: isker