roles/named: Send application logs to syslog

BIND sends its normal application logs (as opposed to query logs) to the
`default_debug` channel.  By sending these log messages to syslog, they
can be routed and rotated using the normal system policies.  Using a
separate dedicated log file just ends up consuming a lot of space, as it
is not managed by any policy.

roles/named/templates/named.conf.j2

@@ -73,10 +73,10 @@ options {
 };
 
 logging {
-        channel default_debug {
+	channel default_debug {
-                file "data/named.run";
+		syslog daemon;
-                severity dynamic;
+		severity dynamic;
-        };
+	};
 {% if named_queries_syslog %}
 	channel queries_syslog {
 		syslog daemon;