More rows.Close() and rows.Err() (#3262)

Looks like we missed some `rows.Close()`

Even though `rows.Err()` is mostly not necessary, we should be more
consistent in the DB layer.

[skip ci]

relayapi/storage/postgres/relay_queue_json_table.go

@@ -109,5 +109,5 @@ func (s *relayQueueJSONStatements) SelectQueueJSON(
 		}
 		blobs[nid] = blob
 	}
-	return blobs, err
+	return blobs, rows.Err()
 }

relayapi/storage/sqlite3/relay_queue_json_table.go

@@ -133,5 +133,5 @@ func (s *relayQueueJSONStatements) SelectQueueJSON(
 		}
 		blobs[nid] = blob
 	}
-	return blobs, err
+	return blobs, rows.Err()
 }