fix: Allow disabling instance refresh on self-managed node groups (part deux)

[bryantbiggs]

Description

• Allow disabling instance refresh on self-managed node groups (part deux). Maintains current default behavior; users can disable with instance_refresh = {}

Motivation and Context

• Resolves Cannot disable instance_refresh in self-managed-node-group since v21.x #3460

Breaking Changes

• No

How Has This Been Tested?

• I have updated at least one of the examples/* to demonstrate and validate my change(s)
• I have tested and validated these changes using one or more of the provided examples/* projects

• I have executed pre-commit run -a on my pull request

[antonbabenko]

This PR is included in version 21.0.9 🎉

[cpanixperi]

Hi,
I guess this is something broke on my prod system.
I am not pinning any version for terraform-aws-modules. It was working fine till y'day . But today I see this error.
Downloading registry.terraform.io/terraform-aws-modules/iam/aws 6.0.0 for my_cluster.eks.iam_eks_role...

• my_cluster.eks.iam_eks_role in .terraform/modules/my_cluster.eks.iam_eks_role/modules/iam-role-for-service-accounts-eks
  ╷
  │ Error: Unreadable module directory
  │
  │ The directory
  │ .terraform/modules/my_cluster.eks.iam_eks_role/modules/iam-role-for-service-accounts-eks
  │ could not be read. This is a bug in Terraform and should be reported.

[bryantbiggs]

Hi, I guess this is something broke on my prod system. I am not pinning any version for terraform-aws-modules. It was working fine till y'day . But today I see this error. Downloading registry.terraform.io/terraform-aws-modules/iam/aws 6.0.0 for my_cluster.eks.iam_eks_role...

* my_cluster.eks.iam_eks_role in .terraform/modules/my_cluster.eks.iam_eks_role/modules/iam-role-for-service-accounts-eks
  ╷
  │ Error: Unreadable module directory
  │
  │ The directory
  │ .terraform/modules/my_cluster.eks.iam_eks_role/modules/iam-role-for-service-accounts-eks
  │ could not be read. This is a bug in Terraform and should be reported.

1. The module shown in your error is the IAM module, not this module (EKS)
2. It broke because you are not specifying a version at all - thats always going to be painful but completely within your control
3. None of it is related to this change here