indexes nodes' contact infos in crds table (#13553)

In several places in gossip code, the entire crds table is scanned only
to filter out nodes' contact infos. Currently on mainnet, crds table is
of size ~70k, while there are only ~470 nodes. So the full table scan is
inefficient. Instead we may maintain an index of only nodes' contact
infos.

core/benches/crds.rs

@@ -17,7 +17,7 @@ fn bench_find_old_labels(bencher: &mut Bencher) {
     let mut rng = thread_rng();
     let mut crds = Crds::default();
     let now = CRDS_GOSSIP_PULL_CRDS_TIMEOUT_MS + CRDS_GOSSIP_PULL_CRDS_TIMEOUT_MS / 1000;
-    std::iter::repeat_with(|| (CrdsValue::new_rand(&mut rng), rng.gen_range(0, now)))
+    std::iter::repeat_with(|| (CrdsValue::new_rand(&mut rng, None), rng.gen_range(0, now)))
         .take(50_000)
         .for_each(|(v, ts)| assert!(crds.insert(v, ts).is_ok()));
     let mut timeouts = HashMap::new();

core/benches/crds_gossip_pull.rs

@@ -39,7 +39,7 @@ fn bench_build_crds_filters(bencher: &mut Bencher) {
     let mut num_inserts = 0;
     for _ in 0..90_000 {
         if crds
-            .insert(CrdsValue::new_rand(&mut rng), rng.gen())
+            .insert(CrdsValue::new_rand(&mut rng, None), rng.gen())
             .is_ok()
         {
             num_inserts += 1;