Disable the automatic poolSize option

it creates more issues than benefits

src/main/java/fr/xephi/authme/datasource/MySQL.java

@@ -98,9 +98,6 @@ public class MySQL implements DataSource {
         this.col = new Columns(settings);
         this.sqlExtension = extensionsFactory.buildExtension(col);
         this.poolSize = settings.getProperty(DatabaseSettings.MYSQL_POOL_SIZE);
-        if (poolSize == -1) {
-            poolSize = Utils.getCoreCount() * 3;
-        }
         this.maxLifetime = settings.getProperty(DatabaseSettings.MYSQL_CONNECTION_MAX_LIFETIME);
         this.useSsl = settings.getProperty(DatabaseSettings.MYSQL_USE_SSL);
     }
@@ -116,7 +113,6 @@ public class MySQL implements DataSource {
         ds.setMaximumPoolSize(poolSize);
         ds.setMaxLifetime(maxLifetime * 1000);
 
-
         // Database URL
         ds.setJdbcUrl("jdbc:mysql://" + this.host + ":" + this.port + "/" + this.database);