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>

common/monitoring_api/src/lib.rs

@@ -128,7 +128,7 @@ impl MonitoringHttpClient {
             Error::BeaconMetricsFailed("Beacon metrics require db path".to_string())
         })?;
 
-        let freezer_db_path = self.db_path.as_ref().ok_or_else(|| {
+        let freezer_db_path = self.freezer_db_path.as_ref().ok_or_else(|| {
             Error::BeaconMetricsFailed("Beacon metrics require freezer db path".to_string())
         })?;
         let metrics =