refactor(swarm-test): don't implicitly add external addresses

This is a safer default than always adding the memory address as external. Kademlia for example depends on whether we have an external address.

Motivated-by: libp2p#4735.

Pull-Request: libp2p#4743.

tests/test_client.rs

@@ -155,7 +155,7 @@ async fn test_confidence() {
     // Randomly test either for public or for private status the confidence.
     let test_public = rand::random::<bool>();
     if test_public {
-        client.listen().await;
+        client.listen().with_memory_addr_external().await;
     } else {
         let unreachable_addr = "/ip4/127.0.0.1/tcp/42".parse().unwrap();
         client.behaviour_mut().probe_address(unreachable_addr);