Restore logrotate cron job in CI

The infra images in the gate have the logrotate package installed
on CentOS, but the cron job file has been removed. This patch
ensures that the cron job is present in the OpenStack gate.

Logrotate is installed by default on CentOS/RHEL 7 systems, so this
won't cause issues on non-test systems.

Change-Id: I4b4cdbe4f36a957ae3c75b210a9df1f67d5c4127

tests/test.yml

@@ -20,6 +20,12 @@
       apt:
         update_cache: yes
       when: ansible_pkg_mgr == 'apt'
+    - name: Ensure OpenStack CI image has a logrotate cron job
+      file:
+        path: /etc/cron.daily/logrotate
+        state: touch
+      when: ansible_os_family == 'RedHat'
+      changed_when: False
   post_tasks:
     - name: Stat 20auto-upgrades file
       stat: