add missing KZQ_REGISTRAR_FLUSH db query definition

(cherry picked from commit 8a04441266)

kamailio/db_queries_kazoo.cfg

@@ -28,3 +28,5 @@
 
 #!substdef "!KZQ_RESET_PUBLISHER_ZONE_UPDATE!INSERT INTO tmp_probe select distinct a.event, a.presentity_uri, 0 from presentities a inner join wdispatcher c on a.sender = c.destination inner join active_watchers b on a.presentity_uri = b.presentity_uri and a.event = b.event where zone = \"\$var(Zone)\" and state in('early', 'confirmed', 'onthephone', 'busy', 'ringing')!g"
 #!substdef "!KZQ_PRESENCE_ZONE_RESET!delete from presentity where id in(select a.id from presentities a join wdispatcher c on a.sender = c.destination where zone = \"\$var(Zone)\")!g"
+
+#!substdef "!KZQ_REGISTRAR_FLUSH!select username || \"@\" || domain as aor, ruid from location where domain = \"\$var(Domain)\"!g"