Do not call writer.flush() in IOUtils.closeSilently(Writer)

This call is not required before close() and it will prevent closing of writer
if write fails for some reason.

h2/src/main/org/h2/util/IOUtils.java

@@ -271,7 +271,6 @@ public class IOUtils {
     public static void closeSilently(Writer writer) {
         if (writer != null) {
             try {
-                writer.flush();
                 writer.close();
             } catch (Exception e) {
                 // ignore