fix shutdown of pending StressSpec, #21960 (#21963)

akka-cluster/src/multi-jvm/scala/akka/cluster/NodeChurnSpec.scala

@@ -107,10 +107,8 @@ abstract class NodeChurnSpec
 
   def isArteryEnabled: Boolean = RARP(system).provider.remoteSettings.Artery.Enabled
 
-  // FIXME issue #21483
-  if (isArteryEnabled) pending
-
   "Cluster with short lived members" must {
+
     "setup stable nodes" taggedAs LongRunningTest in within(15.seconds) {
       val logListener = system.actorOf(Props(classOf[LogListener], testActor), "logListener")
       system.eventStream.subscribe(logListener, classOf[Info])
@@ -119,6 +117,10 @@ abstract class NodeChurnSpec
       enterBarrier("stable")
     }
 
+    // FIXME issue #21483
+    // note: there must be one test step before pending, otherwise afterTermination will not run
+    if (isArteryEnabled) pending
+
     "join and remove transient nodes without growing gossip payload" taggedAs LongRunningTest in {
       // This test is configured with log-frame-size-exceeding and the LogListener
       // will send to the testActor if unexpected increase in message payload size.