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_sim_alt_events.c

@@ -603,7 +603,6 @@ static char* run_sim_and_capture_stdout(const char* base_path,
     memset(&args, 0, sizeof(args));
     args.replay_path     = base_path;
     args.sim_start_ts    = SCHED_SIM_START_TS_LATEST;
-    args.sim_speed       = 0; /* frozen -- deterministic, no wall-clock wait */
     args.alt_events_path = alt_path;
 
     *out_rc = sched_sim_driver_run(&sim, &args);