Prevent instantiation of NamedParameterBatchUpdateUtils

In order to prevent instantiation of utility classes, this commit
makes NamedParameterBatchUpdateUtils `abstract`.

Issue: SPR-17215

Author: sjh836

spring-jdbc/src/main/java/org/springframework/jdbc/core/namedparam/NamedParameterBatchUpdateUtils.java

@@ -30,7 +30,7 @@
  * @author Thomas Risberg
  * @since 3.0
  */
-public class NamedParameterBatchUpdateUtils extends BatchUpdateUtils {
+public abstract class NamedParameterBatchUpdateUtils extends BatchUpdateUtils {
 
 	public static int[] executeBatchUpdateWithNamedParameters(final ParsedSql parsedSql,
 			final SqlParameterSource[] batchArgs, JdbcOperations jdbcOperations) {