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/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)");