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

@@ -1203,8 +1203,12 @@ impl TestRig {
             payload_verification_status: PayloadVerificationStatus::Verified,
             is_valid_merge_transition_block: false,
         };
-        let executed_block =
-            AvailabilityPendingExecutedBlock::new(block, import_data, payload_verification_outcome);
+        let executed_block = AvailabilityPendingExecutedBlock::new(
+            block,
+            import_data,
+            payload_verification_outcome,
+            self.network_globals.custody_columns_count() as usize,
+        );
         match self
             .harness
             .chain

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

@@ -449,7 +449,15 @@ fn build_rpc_block(
             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(),
+                // TODO(das): Assumes CGC = max value. Change if we want to do more complex tests
+                columns.len(),
+                spec,
+            )
+            .unwrap()
         }
         None => RpcBlock::new_without_blobs(None, block),
     }