Remove log output from UDP tracker client

[josecelano]

The console clients that return JSON should not print the log to the console otherwise the printed JSON can't be parsed.

$ cargo run --bin udp_tracker_client announce 144.126.245.19:6969 9c38422213e30bff212b30c360d26f9a02136422 
    Finished `dev` profile [optimized + debuginfo] target(s) in 0.09s
     Running `target/debug/udp_tracker_client announce '144.126.245.19:6969' 9c38422213e30bff212b30c360d26f9a02136422`
2024-06-26T07:46:10.051490Z  INFO torrust_tracker::console::clients::udp::app: logging initialized.
{
  "AnnounceIpv4": {
    "transaction_id": -888840697,
    "announce_interval": 300,
    "leechers": 0,
    "seeders": 1,
    "peers": []
  }
}

We should check if that happens for other clients/requests.