Fernet cron path

Fix the path of fernet cron for centos images

Change-Id: Iedf3a8630bc3c25fd05f580980d499023bf974fa

ansible/roles/keystone/templates/keystone-fernet.json.j2

 {% set cron_cmd = 'cron -f' if kolla_base_distro in ['ubuntu', 'debian'] else 'crond -s -n' %}
+{% set cron_path = '/var/spool/cron/crontabs/root/fernet-cron' if kolla_base_distro in ['ubuntu', 'debian'] else '/var/spool/cron/root' %}
 {
     "command": "{{ cron_cmd }}",
     "config_files": [{
@@ -9,7 +10,7 @@
         },
         {
             "source": "{{ container_config_directory }}/crontab",
-            "dest": "/var/spool/cron/crontabs/root/fernet-cron",
+            "dest": "{{ cron_path }}",
             "owner": "root",
             "perm": "0600"
         },