Disable the automatic poolSize option

it creates more issues than benefits

src/main/java/fr/xephi/authme/util/Utils.java

@@ -96,15 +96,6 @@ public final class Utils {
         return coll == null || coll.isEmpty();
     }
 
-    /**
-     * Return the available core count of the JVM.
-     *
-     * @return the core count
-     */
-    public static int getCoreCount() {
-        return Runtime.getRuntime().availableProcessors();
-    }
-
     /**
      * Returns whether the given email is empty or equal to the standard "undefined" email address.
      *