[query/benches] remove unused declaration
@@ -17,7 +17,6 @@ use common_planners::PlanNode;
use common_runtime::tokio;
use criterion::Criterion;
use datafuse_query::interpreters::SelectInterpreter;
-use datafuse_query::sessions::SessionManager;
use datafuse_query::sql::PlanParser;
use datafuse_query::tests::try_create_session_mgr;
use futures::StreamExt;
