AWS::ElasticLoadBalancingV2::LoadBalancer update bug

## 1. Title
#### AWS::ElasticLoadBalancingV2::LoadBalancer update bug

## 2. Scope of request

When you have a deployment with a Load Balancer (v2), with a listener and an attached target group (a very common case), if a template modification requires a replacement of the ALB (for example changing the exposition mode), it will fail with the following message:
"The following target groups cannot be associated with more than one load balancer: arn:aws:elasticloadbalancing:xxxxxx:xxxxxxxxxxxx:targetgroup/ALBdhqslkdhqskd/flhfkljhfsd (Service: ElasticLoadBalancingV2, Status Code: 400, Request ID: (), Extended Request ID: null)"

This is because CloudFormation doesn't detect that the initial ALB is going to be replaced, and that means the Target Group needs to be replaced as well. As a result, since CloudFormation proceeds by creating a new resource, it tries to attach the Target Group to the new ALB resource, which fails because a Target Group cannot be attached to 2 ALBs at once, and provokes a rollback of the entire stack update.

I found an occurence of this bug in the AWS forums dating back to April 2017:
https://forums.aws.amazon.com/thread.jspa?threadID=254544

## 3. Expected behavior

During AWS::ElasticLoadBalancingV2::LoadBalancer update, if target groups are attached (via listeners) to the ALB being replaced, they should be replaced as well.

As of now, it is not possible to replace a LoadBalancer if a TG is attached to it.

## 4. Suggest specific test cases

Samples:

The link in the AWS support forum has a test template in YAML that helps reproduce the issue. Updating the stack and changing the LB scheme (which provokes a replacement) will trigger the issue.

## 5. Helpful Links to speed up research and evaluation

### https://forums.aws.amazon.com/thread.jspa?threadID=254544

## 6. Category

Networking & Content (VPC, Route53, API GW,...)