playbooks/upgrade-docker-ce: add daemon-reload after package swap

Docker's official package installs dockerd at /usr/bin/dockerd; the
Debian docker.io package put it at /usr/sbin/dockerd. After the apt
swap, the new docker.service unit file is on disk with the right
path, but systemd's cached unit still has the OLD ExecStart pointing
at /usr/sbin/dockerd. Daemon start fails with:

  status=203/EXEC "No such file or directory"

Fix is systemctl daemon-reload between install and start. nh3-docker
hit this; adding the step so esh-docker-vm and ana-docker don't.

playbooks/upgrade-docker-ce.yaml

@@ -126,6 +126,13 @@ steps:
     shell: DEBIAN_FRONTEND=noninteractive apt-get install -y {{ pkgs_to_install }}
     sudo: true
 
+  - name: systemctl daemon-reload (CRITICAL — package swap put dockerd at
+      /usr/bin/dockerd; without reload, systemd keeps the old unit's
+      ExecStart pointing at /usr/sbin/dockerd from docker.io and fails
+      with status=203/EXEC "No such file or directory")
+    shell: systemctl daemon-reload
+    sudo: true
+
   - name: Enable + start the new daemon (idempotent)
     shell: systemctl enable --now docker
     sudo: true