message: chore: rename metric ckb.shared_best_number
diff: @@ -1567,7 +1567,7 @@ impl SyncState {
  self.header_map.contains_key(&header.hash()),
  "HeaderView must exists in header_map before set best header"
  );
  - metrics!(gauge, "ckb-chain.tip_number", header.number() as i64, "type" => "best_header");
  + metrics!(gauge, "ckb.shared_best_number", header.number() as i64);
  *self.shared_best_header.write() = header;
  }
  