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/http_api/create_validator.rs

@@ -97,7 +97,7 @@ pub async fn create_validators<P: AsRef<Path>, T: 'static + SlotClock, E: EthSpe
         let validator_dir = ValidatorDirBuilder::new(validator_dir.as_ref().into())
             .voting_keystore(keystores.voting, voting_password.as_bytes())
             .withdrawal_keystore(keystores.withdrawal, withdrawal_password.as_bytes())
-            .create_eth1_tx_data(request.deposit_gwei, &spec)
+            .create_eth1_tx_data(request.deposit_gwei, spec)
             .store_withdrawal_keystore(false)
             .build()
             .map_err(|e| {