change the timezone precheck task's condition

this ps[0] uses new condition for timezone mounting
but we missed prechecks condition.

[0] https://review.opendev.org/#/c/745505/

Change-Id: I79323a392e171bebe36d06c19d34e458e05e194b
Closes-Bug: #1882553

ansible/roles/prechecks/tasks/datetime_checks.yml

@@ -23,4 +23,4 @@
           /etc/timezone is not found. This file is used for system-wide timezone
           settings and Kolla Ansible needs this file for mounting it to containers.
       when: not etc_timezone.stat.exists
-  when: kolla_base_distro in ['ubuntu', 'debian']
+  when: ansible_os_family == 'Debian'