Start BEEFY client by default for Polkadot nodes (#1913)

Fellowship companion:
https://github.com/polkadot-fellows/runtimes/pull/65

This starts the BEEFY client by default for Polkadot nodes.

Governance/sudo call is later required to enable/start consensus.

Part of https://github.com/paritytech/parity-bridges-common/issues/2420

polkadot/cli/src/command.rs

@@ -195,9 +195,8 @@ where
 		.map_err(Error::from)?;
 	let chain_spec = &runner.config().chain_spec;
 
-	// By default, enable BEEFY on all networks except Polkadot (for now), unless
-	// explicitly disabled through CLI.
-	let mut enable_beefy = !chain_spec.is_polkadot() && !cli.run.no_beefy;
+	// By default, enable BEEFY on all networks, unless explicitly disabled through CLI.
+	let mut enable_beefy = !cli.run.no_beefy;
 	// BEEFY doesn't (yet) support warp sync:
 	// Until we implement https://github.com/paritytech/substrate/issues/14756
 	// - disallow warp sync for validators,

polkadot/node/service/src/lib.rs

@@ -749,11 +749,6 @@ pub fn new_full<OverseerGenerator: OverseerGen>(
 		Some(backoff)
 	};
 
-	// Warn the user that BEEFY is still experimental for Polkadot.
-	if enable_beefy && config.chain_spec.is_polkadot() {
-		gum::warn!("BEEFY is still experimental, usage on Polkadot network is discouraged.");
-	}
-
 	let disable_grandpa = config.disable_grandpa;
 	let name = config.network.node_name.clone();