Fix QBittorrentClient export in legacy qbittorrent.js

Remove undefined QBittorrentClient export that was causing
container startup failures. The actual implementation is now
in server/clients/QBittorrentClient.js

server/utils/qbittorrent.js

@@ -125,11 +125,10 @@ function mapTorrentToDownload(torrent) {
 }
 
 module.exports = {
-  getTorrents: getAllTorrents,
+  getAllTorrents,
   getClients,
   mapTorrentToDownload,
   formatBytes,
   formatSpeed,
-  formatEta,
-  QBittorrentClient
+  formatEta
 };