fix(relay): re-add eBPF channel map entry on refresh (#10291)

TURN channels have a 5 minute cooldown period after they expire where
they cannot be rebound to another peer but can be refreshed and thus
"reactivated".

To stop routing packets when the channel expires, we remove it from the
channel map of the eBPF code. The client however knows that it still has
a channel that it can reactivate for another 5min. In case it chooses to
do so, we refresh the channel in userspace but until now, forget to
re-populate the eBPF map. This effectively blocks this communication
path from working because the relay reports the channel from being
refreshed successfully, yet the new eBPF kernel drops all packets
without a map entry.

rust/relay/server/src/server.rs

@@ -708,6 +708,14 @@ where
                 (sender, requested_channel),
             );
 
+            self.pending_commands
+                .push_back(Command::CreateChannelBinding {
+                    client: sender,
+                    channel_number: requested_channel,
+                    peer: channel.peer_address,
+                    allocation_port: channel.allocation,
+                });
+
             tracing::info!(target: "relay", allocation = %allocation.port, peer = %peer_address, channel = %requested_channel.value(), "Refreshed channel binding");
 
             self.authenticate_and_send(