Adjust oslo_policy include

PROD-33618

Change-Id: I3e0c41884ef1f4ecb4a8ba804e9e426f2af2b81e
diff --git a/designate/files/queens/designate.conf.Debian b/designate/files/queens/designate.conf.Debian
index 854a7c1..671ae05 100644
--- a/designate/files/queens/designate.conf.Debian
+++ b/designate/files/queens/designate.conf.Debian
@@ -416,7 +416,10 @@
 {%- include "oslo_templates/files/queens/oslo/_middleware.conf" %}
 
 [oslo_policy]
+{%- if server.oslo_policy is defined %}
+{%- set _data = server.oslo_policy %}
 {%- include "oslo_templates/files/queens/oslo/_policy.conf" %}
+{%- endif %}
 
 [pool_manager_cache:memcache]