Migrate GCP, DO, Azure to static pod control plane

* Run a kube-apiserver, kube-scheduler, and kube-controller-manager
static pod on each controller node. Previously, kube-apiserver was
self-hosted as a DaemonSet across controllers and kube-scheduler
and kube-controller-manager were a Deployment (with 2 or
controller_count many replicas).
* Remove bootkube bootstrap and pivot to self-hosted
* Remove pod-checkpointer manifests (no longer needed)

bare-metal/container-linux/kubernetes/ssh.tf

@@ -99,7 +99,7 @@ resource "null_resource" "copy-worker-secrets" {
 
   connection {
     type    = "ssh"
-    host    = element(var.worker_domains, count.index)
+    host    = var.worker_domains[count.index]
     user    = "core"
     timeout = "60m"
   }