[Server] Adapt tournament engine to the shared settings message

- read games per match from Command_CreateGame.tournament_settings after the
  proto rework replaced the standalone games_per_match field
- use qWarning to match the surrounding file

libcockatrice_network/libcockatrice/network/server/remote/game/server_game.cpp

@@ -1063,7 +1063,7 @@ void Server_Game::startTournament()
 
         // A tournament with fewer than two players can't produce a valid bracket.
         if (tournament->getPlayerCount() < 2) {
-            qCWarning() << "Cannot start tournament with fewer than 2 players";
+            qWarning() << "Cannot start tournament with fewer than 2 players";
             return;
         }