Add flag to disable cron for test jobs

The run_all cron running in test jobs is unawesome because it can
cause the inventory overrides we put in for the testing to get
overwritten with the real inventory. We don't want test jobs
attempting to run against real hosts.

Change-Id: I733f66ff24b329d193799e6063953e88dd6a35b1

playbooks/roles/ansible-cron/defaults/main.yaml

@@ -4,3 +4,5 @@ update_cron_interval:
   day: '*'
   month: '*'
   weekday: '*'
+# Flag that can be set in tests to ensure cron is not run
+ansible_cron_install_cron: true

playbooks/roles/ansible-cron/tasks/main.yaml

@@ -19,9 +19,10 @@
     day: "{{ update_cron_interval.day }}"
     month: "{{ update_cron_interval.month }}"
     weekday: "{{ update_cron_interval.weekday }}"
+  when: ansible_cron_install_cron
 
 - name: Setup log rotation
   include_role:
     name: logrotate
   vars:
-    logrotate_file_name: /var/log/ansible/run_all_cron.log
+    logrotate_file_name: /var/log/ansible/run_all_cron.log

playbooks/zuul/templates/host_vars/bridge.openstack.org.yaml.j2

@@ -59,3 +59,4 @@ clouds:
   openstackzuul_arm64ci_password: password
   openstackzuul_arm64ci_project_name: project
 gitea_kube_key: Z2l0ZWFfazhzX2tleQ==
+ansible_cron_install_cron: false