Remove redundant API command fetcher

We have our own command listener now, so we don't need to rely on Discord's slow API.

src/main/java/wtf/beatrice/hidekobot/runnables/CommandsUpdateTask.java

@@ -1,25 +0,0 @@
-package wtf.beatrice.hidekobot.runnables;
-
-import net.dv8tion.jda.api.JDA;
-import wtf.beatrice.hidekobot.Cache;
-import wtf.beatrice.hidekobot.HidekoBot;
-import wtf.beatrice.hidekobot.util.Logger;
-
-public class CommandsUpdateTask  implements Runnable {
-
-    private final Logger logger;
-
-    public CommandsUpdateTask()
-    {
-        logger = new Logger(getClass());
-    }
-
-    @Override
-    public void run() {
-        if(Cache.isVerbose()) logger.log("Refreshing commands cache...");
-        JDA instance = HidekoBot.getAPI();
-        if(instance == null) return;
-        Cache.setRegisteredCommands(instance.retrieveCommands().complete());
-        if(Cache.isVerbose()) logger.log("Commands cache refreshed!");
-    }
-}