refactor: remove service_name (#8606)

Which issue # does this PR address?
#8586


  Please list or describe the changes introduced by this PR.
Remove `service_name` from `TaskExecutor`


Co-Authored-By: Abhivansh <31abhivanshj@gmail.com>

testing/simulator/src/basic_sim.rs

@@ -253,7 +253,6 @@ pub fn run_basic_sim(matches: &ArgMatches) -> Result<(), String> {
                         network_1
                             .add_validator_client_with_fallbacks(
                                 validator_config,
-                                i,
                                 beacon_nodes,
                                 files,
                             )