A retry has been added to task controlling secondary master startup.

Fixes #17

There appeared to be a race condition where starting all secondary
masters all at once would cause the k3s service to fail on a number of
the other masters. A retry has been added to the task to attempt to
bring them all up until they stop failing.

tasks/build/configure-k3s-cluster.yml

@@ -53,6 +53,10 @@
     name: k3s
     state: started
     enabled: true
+  register: ensure_secondary_masters_started
+  until: ensure_secondary_masters_started is succeeded
+  retries: "{{ play_hosts | length }}"
+  delay: 2
   when: k3s_control_node and not k3s_primary_control_node
 
 - name: Wait for control plane to be ready to accept connections