+clu #3627 Cluster router group with multiple paths per node

* Use the ordinary routees.paths config property instead of
  cluster.routees-path
* Backwards compatible in deprecation phase

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

@@ -147,9 +147,9 @@ private[cluster] object StressMultiJvmSpec extends MultiNodeConfig {
       /master-node-2/workers {
         router = round-robin-group
         nr-of-instances = 100
+        routees.paths = ["/user/worker"]
         cluster {
           enabled = on
-          routees-path = "/user/worker"
           allow-local-routees = on
         }
       }