Fix getAllNodes cache not working properly, remove pre-process contexts on Bungee & cleanup some unused methods

sponge/src/main/java/me/lucko/luckperms/sponge/LPSpongePlugin.java

@@ -442,11 +442,6 @@ public class LPSpongePlugin implements LuckPermsPlugin {
         return Collections.emptySet();
     }
 
-    @Override
-    public UUID getUuidFromUsername(String playerName) {
-        return game.getServer().getPlayer(playerName).map(Player::getUniqueId).orElse(null);
-    }
-
     @Override
     public List<BaseCommand> getExtraCommands() {
         return Collections.singletonList(new SpongeMainCommand(this));