Adjust ForkJoinPool prefix in HdfsClientThreadLeakFilter (elastic#127534) (elastic#127684)

Adds the ForkJoinPool.commonPool-worker- prefix to the
Thread getName().startsWith() checks in HdfsClientThreadLeakFilter.
This resolves the
"There are still zombie threads that couldn't be terminated"
errors in the Hdfs IT tests.

(cherry picked from commit 4408e38)

Author: JeremyDahlgren

test/fixtures/hdfs-fixture/src/main/java/org/elasticsearch/test/fixtures/hdfs/HdfsClientThreadLeakFilter.java

@@ -35,6 +35,7 @@ public boolean reject(Thread t) {
             || t.getName().startsWith("SSL Certificates Store Monitor") // hadoop 3 brings that in
             || t.getName().startsWith("GcTimeMonitor") // hadoop 3
             || t.getName().startsWith("Command processor") // hadoop 3
-            || t.getName().startsWith("ForkJoinPool-"); // hadoop 3
+            || t.getName().startsWith("ForkJoinPool-") // hadoop 3
+            || t.getName().startsWith("ForkJoinPool.commonPool-worker-"); // hadoop 3
     }
 }