Fix another issue from previous commit

By: md_5 <git@md-5.net>

paper-server/src/main/java/org/bukkit/craftbukkit/CraftServer.java

@@ -1202,7 +1202,6 @@ public final class CraftServer implements Server {
     @Override
     public World getWorld(String name) {
         Preconditions.checkArgument(name != null, "name cannot be null");
-        Preconditions.checkArgument(!name.isBlank(), "name cannot be empty");
 
         return worlds.get(name.toLowerCase(java.util.Locale.ENGLISH));
     }