Clippy 1.49.0 updates and dht persistence test fix (#2156)

## Issue Addressed

`test_dht_persistence` failing

## Proposed Changes

Bind `NetworkService::start` to an underscore prefixed variable rather than `_`.  `_` was causing it to be dropped immediately

This was failing 5/100 times before this update, but I haven't been able to get it to fail after updating it

Co-authored-by: realbigsean <seananderson33@gmail.com>

consensus/types/src/beacon_block.rs

@@ -68,7 +68,7 @@ impl<T: EthSpec> BeaconBlock<T> {
         };
         let indexed_attestation: IndexedAttestation<T> = IndexedAttestation {
             attesting_indices: VariableList::new(vec![
-                0 as u64;
+                0_u64;
                 T::MaxValidatorsPerCommittee::to_usize()
             ])
             .unwrap(),

consensus/types/src/test_utils/builders/testing_attestation_data_builder.rs

@@ -69,7 +69,7 @@ impl TestingAttestationDataBuilder {
             }
             AttestationTestTask::WrongJustifiedCheckpoint => {
                 source = Checkpoint {
-                    epoch: Epoch::from(0 as u64),
+                    epoch: Epoch::from(0_u64),
                     root: Hash256::zero(),
                 }
             }