Fixed anon download test not waiting for port

[qstokkink]

Fixes #8143

This PR:

• Fixes start_anon_download not waiting for listen_ports to be created.

Validated fix with:

diff --git a/src/tribler/core/libtorrent/download_manager/download_manager.py b/src/tribler/core/libtorrent/download_manager/download_manager.py
index 6346306eb..4d71bc241 100644
--- a/src/tribler/core/libtorrent/download_manager/download_manager.py
+++ b/src/tribler/core/libtorrent/download_manager/download_manager.py
@@ -475,7 +475,10 @@ class DownloadManager(TaskManager):
 
         if alert_type == "listen_succeeded_alert":
             ls_alert = cast(lt.listen_succeeded_alert, alert)
-            self.listen_ports[hops][ls_alert.address] = ls_alert.port
+            def do_later(address, port):
+                self.listen_ports[hops][address] = port
+            self.register_anonymous_task("later", do_later, ls_alert.address, ls_alert.port, delay=3)
+            #self.listen_ports[hops][ls_alert.address] = ls_alert.port
 
         elif alert_type == "peer_disconnected_alert":
             self.notifier.notify(Notification.peer_disconnected,