Custody persist fix (#7661)

N/A


  Persist the epoch -> cgc values. This is to ensure that `ValidatorRegistrations::latest_validator_custody_requirement` always returns a `Some` value post restart assuming the `epoch_validator_custody_requirements` map has been updated in the previous runs.

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -654,6 +654,10 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
 
     /// Persists the custody information to disk.
     pub fn persist_custody_context(&self) -> Result<(), Error> {
+        if !self.spec.is_peer_das_scheduled() {
+            return Ok(());
+        }
+
         let custody_context: CustodyContextSsz = self
             .data_availability_checker
             .custody_context()