Clean capella (#4019)

## Issue Addressed

Cleans up all the remnants of 4844 in capella. This makes sure when 4844 is reviewed there is nothing we are missing because it got included here 

## Proposed Changes

drop a bomb on every 4844 thing 

## Additional Info

Merge process I did (locally) is as follows:
- squash merge to produce one commit
- in new branch off unstable with the squashed commit create a `git revert HEAD` commit
- merge that new branch onto 4844 with `--strategy ours`
- compare local 4844 to remote 4844 and make sure the diff is empty
- enjoy

Co-authored-by: Paul Hauner <paul@paulhauner.com>

beacon_node/execution_layer/src/test_utils/handle_rpc.rs

@@ -223,7 +223,6 @@ pub async fn handle_rpc<T: EthSpec>(
                         })
                         .unwrap()
                     }
-                    _ => unreachable!(),
                 }),
                 _ => unreachable!(),
             }