improve logging during initial sync

it is less interesting to see how many rows are written in the db and
more interesting knowing the last height indexed

src/new_index/db.rs

@@ -154,7 +154,7 @@ impl DB {
     }
 
     pub fn write(&self, mut rows: Vec<DBRow>, flush: DBFlush) {
-        debug!(
+        log::trace!(
             "writing {} rows to {:?}, flush={:?}",
             rows.len(),
             self.db,

src/new_index/fetch.rs

@@ -99,6 +99,7 @@ fn bitcoind_fetcher(
                 sender
                     .send(block_entries)
                     .expect("failed to send fetched blocks");
+                log::debug!("last fetch {:?}", entries.last());
             }
         }),
     ))