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>

lcli/src/new_testnet.rs

@@ -10,8 +10,7 @@ use std::path::PathBuf;
 use std::time::{SystemTime, UNIX_EPOCH};
 use types::{
     test_utils::generate_deterministic_keypairs, Address, Config, Epoch, EthSpec,
-    ExecutionPayloadHeader, ExecutionPayloadHeaderCapella, ExecutionPayloadHeaderEip4844,
-    ExecutionPayloadHeaderMerge, ForkName,
+    ExecutionPayloadHeader, ExecutionPayloadHeaderCapella, ExecutionPayloadHeaderMerge, ForkName,
 };
 
 pub fn run<T: EthSpec>(testnet_dir_path: PathBuf, matches: &ArgMatches) -> Result<(), String> {
@@ -94,10 +93,6 @@ pub fn run<T: EthSpec>(testnet_dir_path: PathBuf, matches: &ArgMatches) -> Resul
                             ExecutionPayloadHeaderCapella::<T>::from_ssz_bytes(bytes.as_slice())
                                 .map(ExecutionPayloadHeader::Capella)
                         }
-                        ForkName::Eip4844 => {
-                            ExecutionPayloadHeaderEip4844::<T>::from_ssz_bytes(bytes.as_slice())
-                                .map(ExecutionPayloadHeader::Eip4844)
-                        }
                     }
                     .map_err(|e| format!("SSZ decode failed: {:?}", e))
                 })