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/network/src/subnet_service/tests/mod.rs

@@ -1,4 +1,5 @@
 use super::*;
+use beacon_chain::test_utils::generate_data_column_indices_rand_order;
 use beacon_chain::{
     BeaconChain,
     builder::{BeaconChainBuilder, Witness},
@@ -73,6 +74,9 @@ impl TestBeaconChain {
                     Duration::from_secs(recent_genesis_time()),
                     Duration::from_millis(SLOT_DURATION_MILLIS),
                 ))
+                .ordered_custody_column_indices(generate_data_column_indices_rand_order::<
+                    MainnetEthSpec,
+                >())
                 .shutdown_sender(shutdown_tx)
                 .rng(Box::new(StdRng::seed_from_u64(42)))
                 .build()