Fix clippy errors on tests (#2160)

## Issue Addressed

There are some clippy error on tests.


## Proposed Changes

Enable clippy check on tests and fix the errors. 💪

validator_client/slashing_protection/src/attestation_tests.rs

@@ -306,7 +306,7 @@ fn invalid_surrounding_from_first_source() {
     let second = attestation_data_builder(3, 4);
     StreamTest {
         cases: vec![
-            Test::single(first.clone()),
+            Test::single(first),
             Test::single(second.clone()),
             Test::single(attestation_data_builder(2, 5)).expect_invalid_att(
                 InvalidAttestation::NewSurroundsPrev {
@@ -326,8 +326,8 @@ fn invalid_surrounding_multiple_votes() {
     let third = attestation_data_builder(2, 3);
     StreamTest {
         cases: vec![
-            Test::single(first.clone()),
-            Test::single(second.clone()),
+            Test::single(first),
+            Test::single(second),
             Test::single(third.clone()),
             Test::single(attestation_data_builder(0, 4)).expect_invalid_att(
                 InvalidAttestation::NewSurroundsPrev {

validator_client/slashing_protection/src/block_tests.rs

@@ -69,7 +69,7 @@ fn valid_same_block_different_validator() {
         registered_validators: vec![pubkey(0), pubkey(1)],
         cases: vec![
             Test::with_pubkey(pubkey(0), block.clone()),
-            Test::with_pubkey(pubkey(1), block.clone()),
+            Test::with_pubkey(pubkey(1), block),
         ],
     }
     .run()

validator_client/slashing_protection/src/lib.rs

@@ -119,6 +119,7 @@ mod test {
     use super::*;
 
     #[test]
+    #[allow(clippy::eq_op)]
     fn signing_root_partial_eq() {
         let h0 = SigningRoot(Hash256::zero());
         let h1 = SigningRoot(Hash256::repeat_byte(1));