aws/aws-cdk#9481 has finally been closed, and there is now an L2 [HealthCheck](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.aws_route53.HealthCheck.html) CDK Construct. We should update `HealthCheckAlarmStack` to use this.
aws/aws-cdk#9481 has finally been closed, and there is now an L2 HealthCheck CDK Construct. We should update
HealthCheckAlarmStackto use this.