Revise logging in BlobsByRoot requests (#8296)

#7756 introduces a logging issue, where the relevant log:
https://github.com/sigp/lighthouse/blob/da5b2317205efc72b98cdc922289acefe3f76a13/beacon_node/network/src/network_beacon_processor/rpc_methods.rs#L380-L385

obtains the `block_root` from `slots_by_block_root.keys()`. If the `block_root` is empty (block not found in the data availability checker), then the log will not show any block root:

`DEBUG BlobsByRoot outgoing response processed       peer_id: 16Uiu2HAmCBxs1ZFfsbAfhSA98rUUL8Q1egLPb6WpGdKZxX6HqQYX, block_root: [], returned: 4`

This PR revises to return the `block_root` in the request as a vector of block root


  


Co-Authored-By: Tan Chee Keong <tanck@sigmaprime.io>

Author: chong-he

beacon_node/network/src/network_beacon_processor/rpc_methods.rs

@@ -19,7 +19,7 @@ use lighthouse_tracing::{
 };
 use methods::LightClientUpdatesByRangeRequest;
 use slot_clock::SlotClock;
-use std::collections::{HashMap, hash_map::Entry};
+use std::collections::{HashMap, HashSet, hash_map::Entry};
 use std::sync::Arc;
 use tokio_stream::StreamExt;
 use tracing::{Span, debug, error, field, instrument, warn};
@@ -293,6 +293,9 @@ impl<T: BeaconChainTypes> NetworkBeaconProcessor<T> {
         inbound_request_id: InboundRequestId,
         request: BlobsByRootRequest,
     ) -> Result<(), (RpcErrorResponse, &'static str)> {
+        let requested_roots: HashSet<Hash256> =
+            request.blob_ids.iter().map(|id| id.block_root).collect();
+
         let mut send_blob_count = 0;
 
         let fulu_start_slot = self
@@ -379,7 +382,7 @@ impl<T: BeaconChainTypes> NetworkBeaconProcessor<T> {
 
         debug!(
             %peer_id,
-            block_root = ?slots_by_block_root.keys(),
+            ?requested_roots,
             returned = send_blob_count,
             "BlobsByRoot outgoing response processed"
         );