handle directory flush with cache-only

kamailio/registrar-role.cfg

@@ -355,6 +355,10 @@ event_route[kazoo:consumer-event-directory-reg-flush]
         $sht(auth_cache=>$var(user)) = $null;
     }
 
+    if( $(kzE{kz.json,Cache-Only}) == "true") {
+        return;
+    }
+
     if(reg_fetch_contacts("location", "sip:$var(user)", "caller")) {
        $var(i) = 0;
        while($var(i) < $(ulc(caller=>count))) {