removes redundant epoch stakes cache in retransmit (#14781)

Following d6d76219b, staked nodes computed from vote accounts are
already cached in runtime::Stakes, so the caching in retransmit_stage is
redundant.

core/benches/cluster_info.rs

@@ -35,9 +35,8 @@ fn broadcast_shreds_bench(bencher: &mut Bencher) {
         cluster_info.insert_info(contact_info);
         stakes.insert(id, thread_rng().gen_range(1, NUM_PEERS) as u64);
     }
-    let stakes = Arc::new(stakes);
     let cluster_info = Arc::new(cluster_info);
-    let (peers, peers_and_stakes) = get_broadcast_peers(&cluster_info, Some(stakes));
+    let (peers, peers_and_stakes) = get_broadcast_peers(&cluster_info, Some(&stakes));
     let shreds = Arc::new(shreds);
     let last_datapoint = Arc::new(AtomicU64::new(0));
     bencher.iter(move || {