radicle/config: Do not populate preferred_seeds

Adding the "public seeds" of the network to the `preferred_seeds`
configuration on all nodes causes all nodes to connect to the preferred
seeds and to have them attempt to keep the connection open at all times.

Assuming some growth in the network, and no growth in the number of
"public seeds", this means that the number of inbound connections to the
public seeds grows as well. Once the public seeds are at capacity,
the network as a whole is in some sense bottlenecked by the capacity of
the public seeds: As the network grows further, more and more outbound
connections to the public seeds will fail.

To avoid such issues, do not populate `preferred_seeds`.

crates/radicle/src/profile/config.rs

@@ -157,7 +157,7 @@ impl Config {
 
         Self {
             public_explorer: Explorer::default(),
-            preferred_seeds: node.network.public_seeds(),
+            preferred_seeds: Vec::default(),
             web: web::Config::default(),
             cli: cli::Config::default(),
             node,