Downgrade gossipsub duplicate logs (#5163)

* Downgrade duplicate publish logs

* Maintain backwards compatiblity, deprecate flag

* The tests had to go, because there's no config to test against

* Update help_bn.md

beacon_node/src/cli.rs

@@ -1271,11 +1271,7 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
         .arg(
             Arg::with_name("disable-duplicate-warn-logs")
                 .long("disable-duplicate-warn-logs")
-                .help("Disable warning logs for duplicate gossip messages. The WARN level log is \
-                    useful for detecting a duplicate validator key running elsewhere. However, this may \
-                    result in excessive warning logs if the validator is broadcasting messages to \
-                    multiple beacon nodes via the validator client --broadcast flag. In this case, \
-                    disabling these warn logs may be useful.")
+                .help("This flag is deprecated and has no effect.")
                 .takes_value(false)
         )
         .group(ArgGroup::with_name("enable_http").args(&["http", "gui", "staking"]).multiple(true))

beacon_node/src/config.rs

@@ -1425,9 +1425,6 @@ pub fn set_network_config(
             Some(config_str.parse()?)
         }
     };
-
-    config.disable_duplicate_warn_logs = cli_args.is_present("disable-duplicate-warn-logs");
-
     Ok(())
 }