Ignore or better handle rke_config enable_cri_dockerd

[manning-ncsa]

When I run terraform apply on an otherwise synchronized infrastructure, I always see this:

Terraform will perform the following actions:

  # module.cluster.rancher2_cluster.kube will be updated in-place
  ~ resource "rancher2_cluster" "kube" {
        id                         = "c-x9xrd"
        name                       = "nsf-muses"
        # (16 unchanged attributes hidden)

      ~ rke_config {
          ~ enable_cri_dockerd    = true -> false
            # (5 unchanged attributes hidden)

            # (9 unchanged blocks hidden)
        }

        # (1 unchanged block hidden)
    }

Plan: 0 to add, 1 to change, 0 to destroy.

Let's find a way to account for this so it does not appear as a proposed change.