builtin/aws/ecs: Fix DNS Record creation

[anGie44]

Closes #854

Manual Verification of Record Creation with waypoint built from branch

waypoint.hcl:

app "example-nodejs" {
  labels = {
    "service" = "example-nodejs",
    "env"     = "dev"
  }

  build {
    use "pack" {}
    registry {
      use "aws-ecr" {
        region     = "us-west-2"
        repository = "waypoint-example"
        tag        = "latest"
      }
    }
  }

  deploy {
    use "aws-ecs" {
      region = "us-west-2"
      memory = "512"

      alb {
        listener_arn = ""
        domain_name = "tf-acc-test-7288945550031779998.terraformtest.com"
        zone_id = "XXXXXXXXXX"
        certificate = ""
      }
    }
  }
}

Hosted Zone with NS and SOA Records before waypoint deploy:

 $ waypoint deploy

» Deploying...
✓ Found existing ECS cluster: waypoint
✓ Found existing IAM role to use: ecr-example-nodejs
✓ Using default subnets for Service networking
✓ Modified ALB Listener to introduce target group
✓ Created new Route53 record: tf-acc-test-7288945550031779998.terraformtest.com (zone-id: XXXXXXXXXX)
✓ Configured security group: example-nodejs-inbound-internal
✓ Created ECS Service (example-nodejs-01F2DMACNWP0PRNGG, cluster-name: waypoint)

» Releasing...

» Pruning old deployments...
  Deployment: 01F2DJNX1GZ2JYW3YNBASGFDRH

The deploy was successful! A Waypoint deployment URL is shown below. This
can be used internally to check your deployment and is not meant for external
traffic. You can manage this hostname using "waypoint hostname."

   Release URL: http://tf-acc-test-7288945550031779998.terraformtest.com
Deployment URL: https://only-optimal-elephant--v8.waypoint.run

Hosted Zone Records after waypoint deploy:

Manual Verification of Record Re-use with waypoint built from branch

 $ waypoint deploy

» Deploying...
✓ Found existing ECS cluster: waypoint
✓ Found existing IAM role to use: ecr-example-nodejs
✓ Using default subnets for Service networking
✓ Modified ALB Listener to introduce target group
✓ Found existing Route53 record: tf-acc-test-7288945550031779998.terraformtest.com.
✓ Configured security group: example-nodejs-inbound-internal
✓ Created ECS Service (example-nodejs-01F2DMB8H6DDC5ARW, cluster-name: waypoint)

» Releasing...

» Pruning old deployments...
  Deployment: 01F2DK2FS6VAEHY9RWAFP2VC8E

The deploy was successful! A Waypoint deployment URL is shown below. This
can be used internally to check your deployment and is not meant for external
traffic. You can manage this hostname using "waypoint hostname."

   Release URL: http://tf-acc-test-7288945550031779998.terraformtest.com
Deployment URL: https://only-optimal-elephant--v9.waypoint.run