fix: bring back wait for capella fork epoch (ethpandaops#212)

if someone explicitly sets capella we can have breaks for the default
seconds per slot as seen by @bharath-123 . I am wondering my
`protocolberg` example goes through, I am guessing that reaches epoch 1
as the seconds per slot ar elower

Author: h4ck3rk3y

main.star

@@ -51,12 +51,8 @@ def run(plan, args = {}):
 	for participant in all_participants:
 		all_el_client_contexts.append(participant.el_client_context)
 		all_cl_client_contexts.append(participant.cl_client_context)
-		
 
-	if not args_with_right_defaults.launch_additional_services:
-		return
 
-	
 	mev_endpoints = []
 	# passed external relays get priority
 	# perhaps add mev_type External or remove this
@@ -77,11 +73,22 @@ def run(plan, args = {}):
 		first_cl_client = all_cl_client_contexts[0]
 		first_client_beacon_name = first_cl_client.beacon_service_name
 		mev_flood_module.launch_mev_flood(plan, mev_params.mev_flood_image, el_uri, genesis_constants.PRE_FUNDED_ACCOUNTS)
+		epoch_recipe = GetHttpRequestRecipe(
+				endpoint = "/eth/v2/beacon/blocks/head",
+				port_id = HTTP_PORT_ID_FOR_FACT,
+				extract = {
+						"epoch": ".data.message.body.attestations[0].data.target.epoch"
+				}
+		)
+		plan.wait(recipe = epoch_recipe, field = "extract.epoch", assertion = ">=", target_value = str(network_params.capella_fork_epoch), timeout = "20m", service_name = first_client_beacon_name)		
 		endpoint = mev_relay_launcher_module.launch_mev_relay(plan, mev_params, network_params.network_id, beacon_uris, genesis_validators_root, builder_uri, network_params.seconds_per_slot, network_params.slots_per_epoch)
 		mev_flood_module.spam_in_background(plan, el_uri, mev_params.mev_flood_extra_args, mev_params.mev_flood_seconds_per_bundle, genesis_constants.PRE_FUNDED_ACCOUNTS)
 		if args_with_right_defaults.mev_params.launch_custom_flood:
 			mev_custom_flood_module.spam_in_background(plan, genesis_constants.PRE_FUNDED_ACCOUNTS[-1].private_key, genesis_constants.PRE_FUNDED_ACCOUNTS[0].address, el_uri)
-		mev_endpoints.append(endpoint)		
+		mev_endpoints.append(endpoint)
+
+	if not args_with_right_defaults.launch_additional_services:
+		return
 
 	plan.print("Launching transaction spammer")
 	tx_spammer_params = args_with_right_defaults.tx_spammer_params