feat(scheduler-sim-discrete-clock): remove the simulator speed argument and shadow copy (task 3.1)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/scheduler/testsuite/test_repl_breakpoints_inspection.c

@@ -2017,7 +2017,6 @@ static void run_group_d_child(const char* replay_path,
     memset(&args, 0, sizeof(args));
     args.replay_path  = replay_path;
     args.sim_start_ts = SCHED_SIM_START_TS_LATEST;
-    args.sim_speed    = 0;
     args.interactive  = true;
 
     (void)sched_sim_driver_run(&sim, &args);