use localhost:9663 as default asset domain

conf/base.conf

@@ -6,10 +6,10 @@ mongodb {
 net {
   domain = "localhost:9663"
   socket.domain = ${net.domain}
+  asset.domain = ${net.domain}
   protocol = "http://"
   base_url = ${net.protocol}${net.domain}
   ip = "5.196.91.160"
-  asset.domain = "lichess-assets.local"
   email = "contact@lichess.org"
   crawlable = false
   ratelimit = true