Shut down LOCKSS stack before loading secrets.

Docker secrets cannot be changed (at least through the Ansible module)
while their are in use.

This breaks idempotency.

roles/lockss/tasks/main.yml

@@ -157,6 +157,13 @@
       LOCKSS_TMPDIR=/tmp
       LOCKSS_CLEAR_TMPDIR=no
 
+- name: Shut down LOCKSS containers.
+  command:
+    cmd: scripts/shutdown-lockss
+    chdir: /usr/src/lockss
+  become: true
+  become_user: lockss
+
 - name: Add Docker secret for UI password.
   vars:
     ansible_python_interpreter: python3