CR: Stop netty leak logger on shutdown

Author: original-brownbear

test/framework/src/main/java/org/elasticsearch/test/ESTestCase.java

@@ -219,6 +219,7 @@ public void append(LogEvent event) {
 
         // shutdown hook so that when the test JVM exits, logging is shutdown too
         Runtime.getRuntime().addShutdownHook(new Thread(() -> {
+            leakAppender.stop();
             LoggerContext context = (LoggerContext) LogManager.getContext(false);
             Configurator.shutdown(context);
         }));