Truncated Display impl for ExecutionBlockHash (#9108)

- #6689


  The intention is to only modify the INFO logs that's emitted regularly to reduce the verbosity. But I understand that this change will affect other display in the logs too that uses the `ExecutionBlockHash` display. So would love some feedbacks about the change.


Co-Authored-By: Tan Chee Keong <tanck@sigmaprime.io>

Co-Authored-By: Mac L <mjladson@pm.me>

beacon_node/client/src/notifier.rs

@@ -374,7 +374,7 @@ pub fn spawn_notifier<T: BeaconChainTypes>(
                         warn!(
                             info = "chain not fully verified, \
                             block and attestation production disabled until execution engine syncs",
-                        execution_block_hash = ?hash,
+                            execution_block_hash = ?hash,
                             "Head is optimistic"
                         );
                         format!("{} (unverified)", hash)