Remove HeaderBackend requirement from AuthorityDiscovery and NetworkWorker (#13730)

* Remove `HeaderBackend` requirement from `NetworkWorker`

* Remove HeaderBackend from authority-discovery

substrate/client/network/test/src/lib.rs

@@ -83,7 +83,7 @@ use sp_core::H256;
 use sp_runtime::{
 	codec::{Decode, Encode},
 	generic::BlockId,
-	traits::{Block as BlockT, Header as HeaderT, NumberFor},
+	traits::{Block as BlockT, Header as HeaderT, NumberFor, Zero},
 	Justification, Justifications,
 };
 use substrate_test_runtime_client::AccountKeyring;
@@ -916,13 +916,15 @@ where
 		let sync_service_import_queue = Box::new(sync_service.clone());
 		let sync_service = Arc::new(sync_service.clone());
 
-		let network = NetworkWorker::new(sc_network::config::Params {
+		let genesis_hash =
+			client.hash(Zero::zero()).ok().flatten().expect("Genesis block exists; qed");
+		let network = NetworkWorker::new::<Block>(sc_network::config::Params {
 			role: if config.is_authority { Role::Authority } else { Role::Full },
 			executor: Box::new(|f| {
 				tokio::spawn(f);
 			}),
 			network_config,
-			chain: client.clone(),
+			genesis_hash,
 			protocol_id,
 			fork_id,
 			metrics_registry: None,