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/lighthouse_network/src/config.rs

@@ -157,10 +157,6 @@ pub struct Config {
 
     /// Configuration for the inbound rate limiter (requests received by this node).
     pub inbound_rate_limiter_config: Option<InboundRateLimiterConfig>,
-
-    /// Whether to disable logging duplicate gossip messages as WARN. If set to true, duplicate
-    /// errors will be logged at DEBUG level.
-    pub disable_duplicate_warn_logs: bool,
 }
 
 impl Config {
@@ -378,7 +374,6 @@ impl Default for Config {
             outbound_rate_limiter_config: None,
             invalid_block_storage: None,
             inbound_rate_limiter_config: None,
-            disable_duplicate_warn_logs: false,
         }
     }
 }