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>

testing/ef_tests/src/case_result.rs

@@ -41,7 +41,7 @@ pub fn compare_beacon_state_results_without_caches<T: EthSpec, E: Debug>(
         expected.drop_all_caches().unwrap();
     }
 
-    compare_result_detailed(&result, &expected)
+    compare_result_detailed(result, expected)
 }
 
 /// Same as `compare_result`, however utilizes the `CompareFields` trait to give a list of

testing/ef_tests/src/cases/epoch_processing.rs

@@ -129,8 +129,8 @@ impl<E: EthSpec> EpochTransition<E> for Slashings {
     fn run(state: &mut BeaconState<E>, spec: &ChainSpec) -> Result<(), EpochProcessingError> {
         match state {
             BeaconState::Base(_) => {
-                let mut validator_statuses = base::ValidatorStatuses::new(&state, spec)?;
-                validator_statuses.process_attestations(&state)?;
+                let mut validator_statuses = base::ValidatorStatuses::new(state, spec)?;
+                validator_statuses.process_attestations(state)?;
                 process_slashings(
                     state,
                     validator_statuses.total_balances.current_epoch(),

testing/ef_tests/src/cases/rewards.rs

@@ -53,7 +53,7 @@ type Accessor = fn(&AttestationDelta) -> Δ
 
 fn load_optional_deltas_file(path: &Path) -> Result<Option<Deltas>, Error> {
     let deltas = if path.is_file() {
-        Some(ssz_decode_file(&path)?)
+        Some(ssz_decode_file(path)?)
     } else {
         None
     };

testing/ef_tests/src/results.rs

@@ -11,7 +11,7 @@ pub fn assert_tests_pass(handler_name: &str, path: &Path, results: &[CaseResult]
             &failed,
             &skipped_bls,
             &skipped_known_failures,
-            &results,
+            results,
         );
         if !failed.is_empty() {
             panic!("Tests failed (see above)");