Rust 1.54.0 lints (#2483)

## Issue Addressed

N/A

## Proposed Changes

- Removing a bunch of unnecessary references
- Updated `Error::VariantError` to `Error::Variant`
- There were additional enum variant lints that I ignored, because I thought our variant names were fine
- removed `MonitoredValidator`'s `pubkey` field, because I couldn't find it used anywhere. It looks like we just use the string version of the pubkey (the `id` field) if there is no index

## Additional Info



Co-authored-by: realbigsean <seananderson33@gmail.com>

validator_client/src/duties_service.rs

@@ -378,7 +378,7 @@ async fn poll_beacon_attesters<T: SlotClock + 'static, E: EthSpec>(
 
     // Download the duties and update the duties for the current epoch.
     if let Err(e) = poll_beacon_attesters_for_epoch(
-        &duties_service,
+        duties_service,
         current_epoch,
         &local_indices,
         &local_pubkeys,
@@ -402,7 +402,7 @@ async fn poll_beacon_attesters<T: SlotClock + 'static, E: EthSpec>(
 
     // Download the duties and update the duties for the next epoch.
     if let Err(e) =
-        poll_beacon_attesters_for_epoch(&duties_service, next_epoch, &local_indices, &local_pubkeys)
+        poll_beacon_attesters_for_epoch(duties_service, next_epoch, &local_indices, &local_pubkeys)
             .await
     {
         error!(
@@ -431,7 +431,7 @@ async fn poll_beacon_attesters<T: SlotClock + 'static, E: EthSpec>(
             .attesters
             .read()
             .iter()
-            .filter_map(|(_, map)| map.get(&epoch))
+            .filter_map(|(_, map)| map.get(epoch))
             // The BN logs a warning if we try and subscribe to current or near-by slots. Give it a
             // buffer.
             .filter(|(_, duty_and_proof)| {
@@ -636,7 +636,7 @@ async fn poll_beacon_proposers<T: SlotClock + 'static, E: EthSpec>(
         current_slot,
         &initial_block_proposers,
         block_service_tx,
-        &log,
+        log,
     )
     .await;
 
@@ -723,7 +723,7 @@ async fn poll_beacon_proposers<T: SlotClock + 'static, E: EthSpec>(
                 current_slot,
                 &additional_block_producers,
                 block_service_tx,
-                &log,
+                log,
             )
             .await;
             debug!(