Refactor timestamp_now (#9094)

#9077


  Where possible replaces all instances of `validator_monitor::timestamp_now` with `chain.slot_clock.now_duration().unwrap_or_default()`.
Where chain/slot_clock is not available, instead replace it with a convenience function `slot_clock::timestamp_now`.
Remove the `validator_monitor::timestamp_now` function.


Co-Authored-By: Mac L <mjladson@pm.me>

beacon_node/network/src/sync/network_context/custody.rs

@@ -2,11 +2,11 @@ use crate::sync::network_context::{
     DataColumnsByRootRequestId, DataColumnsByRootSingleBlockRequest,
 };
 use beacon_chain::BeaconChainTypes;
-use beacon_chain::validator_monitor::timestamp_now;
 use fnv::FnvHashMap;
 use lighthouse_network::PeerId;
 use lighthouse_network::service::api_types::{CustodyId, DataColumnsByRootRequester};
 use parking_lot::RwLock;
+use slot_clock::SlotClock;
 use std::collections::HashSet;
 use std::hash::{BuildHasher, RandomState};
 use std::time::{Duration, Instant};
@@ -223,7 +223,10 @@ impl<T: BeaconChainTypes> ActiveCustodyRequest<T> {
                 .collect::<Result<Vec<_>, _>>()?;
 
             let peer_group = PeerGroup::from_set(peers);
-            let max_seen_timestamp = seen_timestamps.into_iter().max().unwrap_or(timestamp_now());
+            let max_seen_timestamp = seen_timestamps
+                .into_iter()
+                .max()
+                .unwrap_or_else(|| cx.chain.slot_clock.now_duration().unwrap_or_default());
             return Ok(Some((columns, peer_group, max_seen_timestamp)));
         }
 

beacon_node/network/src/sync/network_context/requests.rs

@@ -1,9 +1,9 @@
 use std::time::Instant;
 use std::{collections::hash_map::Entry, hash::Hash};
 
-use beacon_chain::validator_monitor::timestamp_now;
 use fnv::FnvHashMap;
 use lighthouse_network::PeerId;
+use slot_clock::timestamp_now;
 use strum::IntoStaticStr;
 use tracing::{Span, debug};
 use types::{Hash256, Slot};