pulumi-eks: Changing the instanceType in an existing NodeGroup results in a 400 failure to delete the LaunchConfig since it is attached to an active ASG

When a NodeGroup is stood up with a given instance type, e.g. t2.medium, and then on a future update is changed to say t3.large, results in the following error:

Diagnostics:
  aws:ec2:LaunchConfiguration (update-existing-nodegroup-ng-2-ondemand-large-nodeLaunchConfiguration):
    error: Plan apply failed: deleting urn:pulumi:dev1::update-existing-nodegroup::eks:index:NodeGroup$aws:ec2/launchConfiguration:LaunchConfiguration::update-existing-nodegroup-ng-2-ondemand-large-nodeLaunchConfiguration: 
    error deleting Autoscaling Launch Configuration (update-existing-nodegroup-ng-2-ondemand-large-nodeLaunchConfiguration-d0932eb):
    ResourceInUse: Cannot delete launch configuration update-existing-nodegroup-ng-2-ondemand-large-nodeLaunchConfiguration-d0932eb because it is attached to AutoScalingGroup update-existing-nodegroup-ng-2-ondemand-large-6410fe15-NodeGroup-1DIVWWS4FCMIU
    status code: 400, request id: f7bfd557-9505-11e9-b696-8ff9971bc5b3

See:

• Issue in https://github.com/terraform-providers/terraform-provider-aws/issues/8485
• TF work-around, but does not work in pulumi/eks as we do not expose namePrefix as an opt in aws.ec2.LaunchConfiguration
• Changing the name of the LaunchConfig resulted in the same error

Manual clean up of the LaunchConfig in the state snapshot and AWS seems to be the only mitigation I’ve found.

cc @jen20 @lukehoban