Remove CGC from data_availability checker (#7033)

- Part of https://github.com/sigp/lighthouse/issues/6767

Validator custody makes the CGC and set of sampling columns dynamic. Right now this information is stored twice:
- in the data availability checker
- in the network globals

If that state becomes dynamic we must make sure it is in sync updating it twice, or guarding it behind a mutex. However, I noted that we don't really have to keep the CGC inside the data availability checker. All consumers can actually read it from the network globals, and we can update `make_available` to read the expected count of data columns from the block.

beacon_node/beacon_chain/src/block_verification.rs

@@ -683,6 +683,7 @@ pub struct GossipVerifiedBlock<T: BeaconChainTypes> {
     pub block_root: Hash256,
     parent: Option<PreProcessingSnapshot<T::EthSpec>>,
     consensus_context: ConsensusContext<T::EthSpec>,
+    custody_columns_count: usize,
 }
 
 /// A wrapper around a `SignedBeaconBlock` that indicates that all signatures (except the deposit
@@ -718,6 +719,7 @@ pub trait IntoGossipVerifiedBlock<T: BeaconChainTypes>: Sized {
     fn into_gossip_verified_block(
         self,
         chain: &BeaconChain<T>,
+        custody_columns_count: usize,
     ) -> Result<GossipVerifiedBlock<T>, BlockError>;
     fn inner_block(&self) -> Arc<SignedBeaconBlock<T::EthSpec>>;
 }
@@ -726,6 +728,7 @@ impl<T: BeaconChainTypes> IntoGossipVerifiedBlock<T> for GossipVerifiedBlock<T>
     fn into_gossip_verified_block(
         self,
         _chain: &BeaconChain<T>,
+        _custody_columns_count: usize,
     ) -> Result<GossipVerifiedBlock<T>, BlockError> {
         Ok(self)
     }
@@ -738,8 +741,9 @@ impl<T: BeaconChainTypes> IntoGossipVerifiedBlock<T> for Arc<SignedBeaconBlock<T
     fn into_gossip_verified_block(
         self,
         chain: &BeaconChain<T>,
+        custody_columns_count: usize,
     ) -> Result<GossipVerifiedBlock<T>, BlockError> {
-        GossipVerifiedBlock::new(self, chain)
+        GossipVerifiedBlock::new(self, chain, custody_columns_count)
     }
 
     fn inner_block(&self) -> Arc<SignedBeaconBlock<T::EthSpec>> {
@@ -808,6 +812,7 @@ impl<T: BeaconChainTypes> GossipVerifiedBlock<T> {
     pub fn new(
         block: Arc<SignedBeaconBlock<T::EthSpec>>,
         chain: &BeaconChain<T>,
+        custody_columns_count: usize,
     ) -> Result<Self, BlockError> {
         // If the block is valid for gossip we don't supply it to the slasher here because
         // we assume it will be transformed into a fully verified block. We *do* need to supply
@@ -817,12 +822,14 @@ impl<T: BeaconChainTypes> GossipVerifiedBlock<T> {
         // The `SignedBeaconBlock` and `SignedBeaconBlockHeader` have the same canonical root,
         // but it's way quicker to calculate root of the header since the hash of the tree rooted
         // at `BeaconBlockBody` is already computed in the header.
-        Self::new_without_slasher_checks(block, &header, chain).map_err(|e| {
-            process_block_slash_info::<_, BlockError>(
-                chain,
-                BlockSlashInfo::from_early_error_block(header, e),
-            )
-        })
+        Self::new_without_slasher_checks(block, &header, chain, custody_columns_count).map_err(
+            |e| {
+                process_block_slash_info::<_, BlockError>(
+                    chain,
+                    BlockSlashInfo::from_early_error_block(header, e),
+                )
+            },
+        )
     }
 
     /// As for new, but doesn't pass the block to the slasher.
@@ -830,6 +837,7 @@ impl<T: BeaconChainTypes> GossipVerifiedBlock<T> {
         block: Arc<SignedBeaconBlock<T::EthSpec>>,
         block_header: &SignedBeaconBlockHeader,
         chain: &BeaconChain<T>,
+        custody_columns_count: usize,
     ) -> Result<Self, BlockError> {
         // Ensure the block is the correct structure for the fork at `block.slot()`.
         block
@@ -1036,6 +1044,7 @@ impl<T: BeaconChainTypes> GossipVerifiedBlock<T> {
             block_root,
             parent,
             consensus_context,
+            custody_columns_count,
         })
     }
 
@@ -1183,6 +1192,7 @@ impl<T: BeaconChainTypes> SignatureVerifiedBlock<T> {
                 block: MaybeAvailableBlock::AvailabilityPending {
                     block_root: from.block_root,
                     block,
+                    custody_columns_count: from.custody_columns_count,
                 },
                 block_root: from.block_root,
                 parent: Some(parent),