Remove peer sampling code (#7768)

Peer sampling has been completely removed from the spec. This PR removes our partial implementation from the codebase.
https://github.com/ethereum/consensus-specs/pull/4393

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -2959,16 +2959,6 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         ChainSegmentResult::Successful { imported_blocks }
     }
 
-    /// Updates fork-choice node into a permanent `available` state so it can become a viable head.
-    /// Only completed sampling results are received. Blocks are unavailable by default and should
-    /// be pruned on finalization, on a timeout or by a max count.
-    pub async fn process_sampling_completed(self: &Arc<Self>, block_root: Hash256) {
-        // TODO(das): update fork-choice, act on sampling result, adjust log level
-        // NOTE: It is possible that sampling complets before block is imported into fork choice,
-        // in that case we may need to update availability cache.
-        info!(%block_root, "Sampling completed");
-    }
-
     /// Returns `Ok(GossipVerifiedBlock)` if the supplied `block` should be forwarded onto the
     /// gossip network. The block is not imported into the chain, it is just partially verified.
     ///
@@ -7043,15 +7033,6 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             && self.spec.is_peer_das_enabled_for_epoch(block_epoch)
     }
 
-    /// Returns true if we should issue a sampling request for this block
-    /// TODO(das): check if the block is still within the da_window
-    pub fn should_sample_slot(&self, slot: Slot) -> bool {
-        self.config.enable_sampling
-            && self
-                .spec
-                .is_peer_das_enabled_for_epoch(slot.epoch(T::EthSpec::slots_per_epoch()))
-    }
-
     /// Gets the `LightClientBootstrap` object for a requested block root.
     ///
     /// Returns `None` when the state or block is not found in the database.

beacon_node/beacon_chain/src/chain_config.rs

@@ -96,8 +96,6 @@ pub struct ChainConfig {
     pub enable_light_client_server: bool,
     /// The number of data columns to withhold / exclude from publishing when proposing a block.
     pub malicious_withhold_count: usize,
-    /// Enable peer sampling on blocks.
-    pub enable_sampling: bool,
     /// Number of batches that the node splits blobs or data columns into during publication.
     /// This doesn't apply if the node is the block proposer. For PeerDAS only.
     pub blob_publication_batches: usize,
@@ -148,7 +146,6 @@ impl Default for ChainConfig {
             epochs_per_migration: crate::migrate::DEFAULT_EPOCHS_PER_MIGRATION,
             enable_light_client_server: true,
             malicious_withhold_count: 0,
-            enable_sampling: false,
             blob_publication_batches: 4,
             blob_publication_batch_interval: Duration::from_millis(300),
             sync_tolerance_epochs: DEFAULT_SYNC_TOLERANCE_EPOCHS,