Range sync: fetch data columns via custody-by-root (#9496)

- Generalize the custody-by-root request to accept a `Vec<Hash256>` of block roots so a whole batch is fetched in one request; `DataColumnsByRootRequestParams { block_roots, indices }` completes at `block_roots.len() * indices.len()`.
- `custody_lookup_request` takes `block_roots: &[Hash256]` + `block_epoch`; `cached_data_column_indexes` takes `block_epoch`.
- `block_sidecar_coupling.rs`: couple a batch's blocks with the columns returned by the single custody-by-root request; drop the per-column request map and retry/faulty-peer machinery.
- Remove the now-unused columns-by-range range-sync path and the serialize-downloads gate.


Co-Authored-By: dapplion <35266934+dapplion@users.noreply.github.com>

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -1203,13 +1203,9 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     pub fn cached_data_column_indexes(
         &self,
         block_root: &Hash256,
-        slot: Slot,
+        block_epoch: Epoch,
     ) -> Option<Vec<ColumnIndex>> {
-        if self
-            .spec
-            .fork_name_at_slot::<T::EthSpec>(slot)
-            .gloas_enabled()
-        {
+        if self.spec.fork_name_at_epoch(block_epoch).gloas_enabled() {
             self.pending_payload_cache
                 .cached_data_column_indexes(block_root)
         } else {
@@ -3494,7 +3490,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                 return;
             };
             let imported_data_columns = self
-                .cached_data_column_indexes(block_root, slot)
+                .cached_data_column_indexes(block_root, slot.epoch(T::EthSpec::slots_per_epoch()))
                 .unwrap_or_default();
             let new_data_columns =
                 data_columns_iter.filter(|b| !imported_data_columns.contains(b.index()));

beacon_node/beacon_chain/src/fetch_blobs/fetch_blobs_beacon_adapter.rs

@@ -10,7 +10,7 @@ use mockall::automock;
 use std::collections::HashSet;
 use std::sync::Arc;
 use task_executor::TaskExecutor;
-use types::{ChainSpec, ColumnIndex, Hash256, Slot};
+use types::{ChainSpec, ColumnIndex, EthSpec, Hash256, Slot};
 
 /// An adapter to the `BeaconChain` functionalities to remove `BeaconChain` from direct dependency to enable testing fetch blobs logic.
 pub(crate) struct FetchBlobsBeaconAdapter<T: BeaconChainTypes> {
@@ -92,7 +92,8 @@ impl<T: BeaconChainTypes> FetchBlobsBeaconAdapter<T> {
         block_root: &Hash256,
         slot: Slot,
     ) -> Option<Vec<u64>> {
-        self.chain.cached_data_column_indexes(block_root, slot)
+        self.chain
+            .cached_data_column_indexes(block_root, slot.epoch(T::EthSpec::slots_per_epoch()))
     }
 
     pub(crate) async fn process_engine_blobs(