Change: [Network] Update server's NetworkServerGameInfo only when needed

Split the updating in a "static" version that only needs to be called when a new map is loaded or some settings are changed, and a "dynamic" version that updates everything that changes regularly such as the current game date or the number of spectators.

src/network/network_server.cpp

@@ -1992,6 +1992,12 @@ void NetworkServerSendConfigUpdate()
 	}
 }
 
+/** Update the server's NetworkServerGameInfo due to changes in settings. */
+void NetworkServerUpdateGameInfo()
+{
+	if (_network_server) FillStaticNetworkServerGameInfo();
+}
+
 /**
  * Tell that a particular company is (not) passworded.
  * @param company_id The company that got/removed the password.