make ESIntegTestCase::awaitGlobalNettyThreadsFinish public (#133549)

Author: richard-dennehy

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

@@ -2640,7 +2640,7 @@ public static void afterClass() throws Exception {
     /**
      *  After the cluster is stopped, there are a few netty threads that can linger, so we make sure we don't leak any tasks on them.
      */
-    static void awaitGlobalNettyThreadsFinish() throws Exception {
+    public static void awaitGlobalNettyThreadsFinish() throws Exception {
         // Don't use GlobalEventExecutor#awaitInactivity. It will waste up to 1s for every call and we expect no tasks queued for it
         // except for the odd scheduled shutdown task.
         assertBusy(() -> assertEquals(0, GlobalEventExecutor.INSTANCE.pendingTasks()));