Disable the automatic poolSize option

it creates more issues than benefits

src/test/java/fr/xephi/authme/util/UtilsTest.java

@@ -117,12 +117,6 @@ public class UtilsTest {
         assertThat(Utils.isCollectionEmpty(null), equalTo(true));
     }
 
-    @Test
-    public void shouldReturnCoreCount() {
-        // given / when / then
-        assertThat(Utils.getCoreCount(), greaterThan(0));
-    }
-
     @Test
     public void shouldLogAndSendWarning() {
         // given