fix: [#1543] Remove peerless torrents when it's enabled in the tracker policy

There were not being removed when stats was enabled becuase the tracker
was counting downloads only from the active swarms.

Now the API exposed metric (global downldoads) is not taken from the
in-memory data structrure unless stats persistence is disabled. In that
case, the global total would be per session (since the tracker started),
and reset when the tracker restarts.

Author: josecelano

packages/torrent-repository/src/swarm.rs

@@ -201,13 +201,7 @@ impl Swarm {
     /// Returns true if the swarm should be removed according to the retention
     /// policy.
     fn should_be_removed(&self, policy: &TrackerPolicy) -> bool {
-        // If the policy is to remove peerless torrents and the swarm is empty (no peers),
-        (policy.remove_peerless_torrents && self.is_empty())
-            // but not when the policy is to persist torrent stats and the 
-            // torrent has been downloaded at least once.
-            // (because the only way to store the counter is to keep the swarm in memory.
-            // See https://github.com/torrust/torrust-tracker/issues/1502)
-            && !(policy.persistent_torrent_completed_stat && self.metadata().downloaded > 0)
+        policy.remove_peerless_torrents && self.is_empty()
     }
 
     fn update_metadata_on_insert(&mut self, added_peer: &Arc<PeerAnnouncement>) {