Handle CoordinatedShutdown exiting-completed when not joined, #26832

* assertion failed: Nodes not part of cluster have marked the Gossip as seen
* trying to mark the Gossip as seen before it has joined, which may happen
  if CoordinatedShutdown is running before the node has joined

akka-cluster/src/main/scala/akka/cluster/ClusterDaemon.scala

@@ -826,6 +826,8 @@ private[cluster] class ClusterCoreDaemon(publisher: ActorRef, joinConfigCompatCh
     logInfo("Exiting completed")
     // ExitingCompleted sent via CoordinatedShutdown to continue the leaving process.
     exitingTasksInProgress = false
+    // status Removed also before joining
+    if (membershipState.selfMember.status != MemberStatus.Removed) {
       // mark as seen
       membershipState = membershipState.seen()
       assertLatestGossip()
@@ -854,6 +856,7 @@ private[cluster] class ClusterCoreDaemon(publisher: ActorRef, joinConfigCompatCh
           }
         case None => // no leader
       }
+    }
 
     shutdown()
   }