fix: Skip retrieving EKS cluster data when not creating the role

[wonko]

Description

Adds an additional conditional in the existing for_each for reading the EKS cluster data and constructing part of the policy document.

(I suppose the whole policy document can be skipped if there's no role being created... but no harm done in keeping it in, didn't want to break other things.)

Motivation and Context

Fixes #324

Breaking Changes

No breaking changes afaik, only adds hardening in the need for the execution of certain resources.

How Has This Been Tested?

Tested with the following code (module is local fork, at the v5.5.1 tag).

module "cluster_autoscaler_role" {
  create_role = false
  source      = "./modules/terraform-aws-iam/modules/iam-eks-role"
  #  version     = "5.5.1" 

  role_name = "cluster-autoscaler-false"

  cluster_service_accounts = {
    "foo" = ["kube-system:cluster-autoscaler"]
  }

  #   role_policy_arns = {
  #     cluster-autoscaler = module.cluster_autoscaler_policy.arn
  #   }
}

Also toggled the create_role to true to validate that the old flow still functions.

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

➜ pre-commit run -a
Terraform fmt............................................................Passed
Terraform wrapper with for_each in module................................Passed
Terraform validate.......................................................Passed
Terraform docs...........................................................Passed
Terraform validate with tflint...........................................Passed
check for merge conflicts................................................Passed
fix end of files.........................................................Passed

[github-actions]

This PR has been automatically marked as stale because it has been open 30 days
with no activity. Remove stale label or comment or this PR will be closed in 10 days

[wonko]

not stale ...

[max-rocket-internet]

Nice

[antonbabenko]

This PR is included in version 5.33.1 🎉

[github-actions]

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