Fix custody context initialization race condition that caused panic (#8391)

Take 2 of #8390.

Fixes the race condition properly instead of propagating the error. I think this is a better alternative, and doesn't seem to look that bad.


  * Lift node id loading or generation from `NetworkService ` startup to the `ClientBuilder`, so that it can be used to compute custody columns for the beacon chain without waiting for Network bootstrap.

I've considered and implemented a few alternatives:
1. passing `node_id` to beacon chain builder and compute columns when creating `CustodyContext`. This approach isn't good for separation of concerns and isn't great for testability
2. passing `ordered_custody_groups` to beacon chain. `CustodyContext` only uses this to compute ordered custody columns, so we might as well lift this logic out, so we don't have to do error handling in `CustodyContext` construction. Less tests to update;.


Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>

beacon_node/src/lib.rs

@@ -9,6 +9,8 @@ pub use client::{Client, ClientBuilder, ClientConfig, ClientGenesis};
 pub use config::{get_config, get_data_dir, set_network_config};
 use environment::RuntimeContext;
 pub use eth2_config::Eth2Config;
+use lighthouse_network::load_private_key;
+use network_utils::enr_ext::peer_id_to_node_id;
 use slasher::{DatabaseBackendOverride, Slasher};
 use std::ops::{Deref, DerefMut};
 use std::sync::Arc;
@@ -120,8 +122,12 @@ impl<E: EthSpec> ProductionBeaconNode<E> {
             builder
         };
 
+        // Generate or load the node id.
+        let local_keypair = load_private_key(&client_config.network);
+        let node_id = peer_id_to_node_id(&local_keypair.public().to_peer_id())?.raw();
+
         let builder = builder
-            .beacon_chain_builder(client_genesis, client_config.clone())
+            .beacon_chain_builder(client_genesis, client_config.clone(), node_id)
             .await?;
         info!("Block production enabled");
 
@@ -133,7 +139,7 @@ impl<E: EthSpec> ProductionBeaconNode<E> {
 
         builder
             .build_beacon_chain()?
-            .network(Arc::new(client_config.network))
+            .network(Arc::new(client_config.network), local_keypair)
             .await?
             .notifier()?
             .http_metrics_config(client_config.http_metrics.clone())