Fix bare-metal multiple apply/ssh on Terraform v0.11.4+

* Terraform v0.11.4 introduced changes to remote-exec
that mean Typhoon bare-metal clusters require multiple
runs of terraform apply to ssh and bootstrap.
* Bare-metal installs PXE boot a live instance to install
to disk and then reboot from disk as controllers/workers.
Terraform remote-exec has no way to "know" to wait until
the reboot has occurred to kickoff Kubernetes bootstrap.
Previously Typhoon created a "debug" user during this
install phase to allow an admin to SSH, but remote-exec
would hang, trying to connect as user "core". Terraform
v0.11.4 changes this behavior so remote-exec fails and
a user must re-run terraform apply until succeeding.
* A new way to "trick" remote-exec into waiting for the
reboot into the disk install is to run SSH on a non-standard
port during the disk install. This retains the ability
for an admin to SSH during install (most distros don't have
this) and fixes the issue so only a single run of terraform
apply is needed.
* https://github.com/hashicorp/terraform/pull/17359#issuecomment-376415464

bare-metal/container-linux/kubernetes/cl/container-linux-install.yaml.tmpl

@@ -12,6 +12,16 @@ systemd:
         ExecStart=/opt/installer
         [Install]
         WantedBy=multi-user.target
+    # Avoid using the standard SSH port so terraform apply cannot SSH until
+    # post-install. But admins may SSH to debug disk install problems.
+    # After install, sshd will use port 22 and users/terraform can connect.
+    - name: sshd.socket
+      dropins:
+        - name: 10-sshd-port.conf
+          contents: |
+            [Socket]
+            ListenStream=
+            ListenStream=2222
 storage:
   files:
     - path: /opt/installer
@@ -32,11 +42,6 @@ storage:
           systemctl reboot
 passwd:
   users:
-    # Avoid using standard name "core" so terraform apply cannot SSH until post-install.
-    - name: debug
-      create:
-        groups:
-          - sudo
-          - docker
+    - name: core
       ssh_authorized_keys:
-        - {{.ssh_authorized_key}}
+        - "${ssh_authorized_key}"