Terraform provider does no handle unsized but enabled ML tiers

[tobio]

Readiness Checklist

• I am running the latest version
• I checked the documentation and found no answer
• I checked to make sure that this issue has not already been filed
• I am reporting the issue to the correct repository (for multi-repository projects)

Expected Behavior

Managing the following resources should create the topology elements once, and then not show any required changed on a subsequent terraform plan

resource "ec_deployment" "staging" {
  region                 = "eu-west-1"
  version                = data.ec_stack.latest.version
  deployment_template_id = "aws-storage-optimized"

  elasticsearch {
    autoscale = "true"

    topology {
      id         = "hot_content"
      size       = "1g"
      zone_count = 3

      autoscaling {
        max_size = "8g"
      }
    }

    topology {
      id         = "ml"
      zone_count = 1

      autoscaling {
        min_size = "0gb"
        max_size = "60gb"
      }
    }
  }

  kibana {
    topology {
      size       = "1g"
      zone_count = 2
    }
  }
}

Current Behavior

The provider does not treat the unsized ML tier as existing, and attempts to create it on each subsequent terraform plan|apply

## Terraform definition

resource "ec_deployment" "staging" {
  region                 = "eu-west-1"
  version                = data.ec_stack.latest.version
  deployment_template_id = "aws-storage-optimized"

  elasticsearch {
    autoscale = "true"

    topology {
      id         = "hot_content"
      size       = "1g"
      zone_count = 3

      autoscaling {
        max_size = "8g"
      }
    }

    topology {
      id         = "ml"
      zone_count = 1

      autoscaling {
        min_size = "0gb"
        max_size = "60gb"
      }
    }
  }

  kibana {
    topology {
      size       = "1g"
      zone_count = 2
    }
  }
}

Steps to Reproduce

1. Use the above resource
2. terraform apply
3. terraform apply