Revert "revert enabling authority discovery by default (#1532)" (#1807)

This reverts commit a7b6c91f80.

The authority discovery module was initially enabled by default on
validator and sentry nodes with commit 59f5eb4. This change was later on
reverted in a7b6c91. With this commit the authority discovery module is
again enabled by default.

polkadot/node/test-service/src/lib.rs

@@ -61,14 +61,14 @@ native_executor_instance!(
 /// Create a new Polkadot test service for a full node.
 pub fn polkadot_test_new_full(
 	config: Configuration,
-	authority_discovery_enabled: bool,
+	authority_discovery_disabled: bool,
 ) -> Result<
 	NewFull<Arc<FullClient<polkadot_test_runtime::RuntimeApi, PolkadotTestExecutor>>>,
 	ServiceError,
 > {
 	new_full::<polkadot_test_runtime::RuntimeApi, PolkadotTestExecutor>(
 		config,
-		authority_discovery_enabled,
+		authority_discovery_disabled,
 		None,
 	).map_err(Into::into)
 }
@@ -192,9 +192,9 @@ pub fn run_test_node(
 > {
 	let config = node_config(storage_update_func, task_executor, key, boot_nodes);
 	let multiaddr = config.network.listen_addresses[0].clone();
-	let authority_discovery_enabled = false;
+	let authority_discovery_disabled = true;
 	let NewFull {task_manager, client, network, rpc_handlers, overseer_handler, ..} =
-		polkadot_test_new_full(config, authority_discovery_enabled)
+		polkadot_test_new_full(config, authority_discovery_disabled)
 			.expect("could not create Polkadot test service");
 
 	let peer_id = network.local_peer_id().clone();