Fix clippy warnings (#2861)

Fix some issues reported by clippy

polkadot/node/subsystem-bench/src/core/keyring.rs

@@ -14,7 +14,6 @@
 // You should have received a copy of the GNU General Public License
 // along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
 
-pub use sp_core::sr25519;
 use sp_core::{
 	sr25519::{Pair, Public},
 	Pair as PairT,

polkadot/node/subsystem-bench/src/core/mock/mod.rs

@@ -23,7 +23,6 @@ pub mod network_bridge;
 pub mod runtime_api;
 
 pub use av_store::*;
-pub use network_bridge::*;
 pub use runtime_api::*;
 
 pub struct AlwaysSupportsParachains {}