use is synced for notifier again

beacon_node/beacon_chain/src/merge_readiness.rs

@@ -163,7 +163,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                 };
             }
 
-            if !el.is_synced().await {
+            if !el.is_synced_for_notifier().await {
                 // The EL is not synced.
                 return MergeReadiness::NotSynced;
             }