SUP-2495: Update Resources to be replaced if Cluster ID changes

[tomowatt]

Agent Tokens and (Default) Queues cannot be moved between Clusters so any attempt via Terraform should force the Resources to be replaced if the Cluster ID changes.

[tomowatt]

This provides an initial fix for: https://github.com/buildkite/terraform-provider-buildkite/issues/553

[tomowatt]

Manual testing with the following setup:

resource "buildkite_cluster" "primary" {
  name        = "Primary cluster"
  description = "Runs the monolith build and deploy"
}

resource "buildkite_cluster" "secondary" {
  name        = "Secondary cluster"
  description = "Runs the 2nd monolith build and deploy"
}

resource "buildkite_cluster_queue" "default" {
  cluster_id = buildkite_cluster.primary.id
  key        = "default"
}

resource "buildkite_cluster_default_queue" "primary" {
  cluster_id = buildkite_cluster.primary.id
  queue_id   = buildkite_cluster_queue.default.id
}

resource "buildkite_cluster_agent_token" "default" {
  description = "Default cluster token"
  cluster_id  = buildkite_cluster.primary.id
}

Then switching cluster_id = buildkite_cluster.primary.id to cluster_id = buildkite_cluster.secondary.id which then causes them to be recreated as the Cluster Queue and Agent Token cannot be moved between Clusters.