1.57.0 lints (#2850)

## Issue Addressed

New rust lints

## Proposed Changes

- Boxing some enum variants
- removing some unused fields (is the validator lockfile unused? seemed so to me)

## Additional Info

- some error fields were marked as dead code but are logged out in areas
- left some dead fields in our ef test code because I assume they are useful for debugging?

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

validator_client/src/config.rs

@@ -131,7 +131,7 @@ impl Config {
         if let Some(beacon_nodes) = parse_optional::<String>(cli_args, "beacon-nodes")? {
             config.beacon_nodes = beacon_nodes
                 .split(',')
-                .map(|s| SensitiveUrl::parse(s))
+                .map(SensitiveUrl::parse)
                 .collect::<Result<_, _>>()
                 .map_err(|e| format!("Unable to parse beacon node URL: {:?}", e))?;
         }

validator_client/src/lib.rs

@@ -84,7 +84,6 @@ pub struct ProductionValidatorClient<T: EthSpec> {
     doppelganger_service: Option<Arc<DoppelgangerService>>,
     validator_store: Arc<ValidatorStore<SystemTimeSlotClock, T>>,
     http_api_listen_addr: Option<SocketAddr>,
-    http_metrics_ctx: Option<Arc<http_metrics::Context<T>>>,
     config: Config,
 }
 
@@ -431,7 +430,6 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
             validator_store,
             config,
             http_api_listen_addr: None,
-            http_metrics_ctx,
         })
     }