Revert special casing of Kusama for grandpa rounds. (#6217)

Co-authored-by: eskimor <eskimor@no-such-url.com>

polkadot/node/service/src/lib.rs

@@ -1221,22 +1221,11 @@ where
 		}
 	}
 
-	// Reduce grandpa load on Kusama and test networks. This will slow down finality by
-	// approximately one slot duration, but will reduce load. We would like to see the impact on
-	// Kusama, see: https://github.com/paritytech/polkadot/issues/5464
-	let gossip_duration = if chain_spec.is_versi() ||
-		chain_spec.is_wococo() ||
-		chain_spec.is_rococo() ||
-		chain_spec.is_kusama()
-	{
-		Duration::from_millis(2000)
-	} else {
-		Duration::from_millis(1000)
-	};
-
 	let config = grandpa::Config {
 		// FIXME substrate#1578 make this available through chainspec
-		gossip_duration,
+		// Grandpa performance can be improved a bit by tuning this parameter, see:
+		// https://github.com/paritytech/polkadot/issues/5464
+		gossip_duration: Duration::from_millis(1000),
 		justification_period: 512,
 		name: Some(name),
 		observer_enabled: false,