Fulu update to spec v1.6.0-alpha.4 (#7890)

Fulu update to spec [v1.6.0-alpha.4](https://github.com/ethereum/consensus-specs/releases/tag/v1.6.0-alpha.4).
- Make `number_of_columns` a preset
- Optimise `get_custody_groups` to avoid computing if cgc = 128
- Add support for additional typenum values in type_dispatch macro

beacon_node/network/src/sync/tests/lookups.rs

@@ -1922,7 +1922,7 @@ fn custody_lookup_happy_path() {
     let id = r.expect_block_lookup_request(block.canonical_root());
     r.complete_valid_block_request(id, block.into(), true);
     // for each slot we download `samples_per_slot` columns
-    let sample_column_count = spec.samples_per_slot * spec.data_columns_per_group();
+    let sample_column_count = spec.samples_per_slot * spec.data_columns_per_group::<E>();
     let custody_ids =
         r.expect_only_data_columns_by_root_requests(block_root, sample_column_count as usize);
     r.complete_valid_custody_request(custody_ids, data_columns, false);

beacon_node/network/src/sync/tests/range.rs

@@ -427,7 +427,7 @@ impl TestRig {
             .chain
             .process_block(
                 block_root,
-                build_rpc_block(block.into(), &data_sidecars, &self.spec),
+                build_rpc_block(block.into(), &data_sidecars),
                 NotifyExecutionLayer::Yes,
                 BlockImportSource::RangeSync,
                 || Ok(()),
@@ -443,14 +443,13 @@ impl TestRig {
 fn build_rpc_block(
     block: Arc<SignedBeaconBlock<E>>,
     data_sidecars: &Option<DataSidecars<E>>,
-    spec: &ChainSpec,
 ) -> RpcBlock<E> {
     match data_sidecars {
         Some(DataSidecars::Blobs(blobs)) => {
             RpcBlock::new(None, block, Some(blobs.clone())).unwrap()
         }
         Some(DataSidecars::DataColumns(columns)) => {
-            RpcBlock::new_with_custody_columns(None, block, columns.clone(), spec).unwrap()
+            RpcBlock::new_with_custody_columns(None, block, columns.clone()).unwrap()
         }
         // Block has no data, expects zero columns
         None => RpcBlock::new_without_blobs(None, block),