Remove some "wontfix" TODOs for the merge (#3449)

## Issue Addressed

NA

## Proposed Changes

Removes three types of TODOs:

1. `execution_layer/src/lib.rs`: It was [determined](https://github.com/ethereum/consensus-specs/issues/2636#issuecomment-988688742) that there is no action required here.
2. `beacon_processor/worker/gossip_methods.rs`: Removed TODOs relating to peer scoring that have already been addressed via `epe.penalize_peer()`.
    - It seems `cargo fmt` wanted to adjust some things here as well 🤷 
3. `proto_array_fork_choice.rs`: it would be nice to remove that useless `bool` for cleanliness, but I don't think it's something we need to do and the TODO just makes things look messier IMO.


## Additional Info

There should be no functional changes to the code in this PR.

There are still some TODOs lingering, those ones require actual changes or more thought.

beacon_node/execution_layer/src/lib.rs

@@ -1267,14 +1267,6 @@ impl<T: EthSpec> ExecutionLayer<T> {
     }
 
     /// Maps to the `eth_getBlockByHash` JSON-RPC call.
-    ///
-    /// ## TODO(merge)
-    ///
-    /// This will return an execution block regardless of whether or not it was created by a PoW
-    /// miner (pre-merge) or a PoS validator (post-merge). It's not immediately clear if this is
-    /// correct or not, see the discussion here:
-    ///
-    /// https://github.com/ethereum/consensus-specs/issues/2636
     async fn get_pow_block(
         &self,
         engine: &Engine,