Add no-useless-constructor eslint rule and fix issues

src/plugins/syncPlay/core/timeSync/TimeSyncServer.js

@@ -9,10 +9,6 @@ import TimeSync from './TimeSync';
  * Class that manages time syncing with server.
  */
 class TimeSyncServer extends TimeSync {
-    constructor(syncPlayManager) {
-        super(syncPlayManager);
-    }
-
     /**
      * Makes a ping request to the server.
      */

src/plugins/syncPlay/ui/players/HtmlAudioPlayer.js

@@ -10,10 +10,6 @@ import HtmlVideoPlayer from './HtmlVideoPlayer';
  */
 class HtmlAudioPlayer extends HtmlVideoPlayer {
     static type = 'htmlaudioplayer';
-
-    constructor(player, syncPlayManager) {
-        super(player, syncPlayManager);
-    }
 }
 
 export default HtmlAudioPlayer;