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_resource_contention.c

@@ -1062,7 +1062,6 @@ static void test_contention_fixture_is_replayable_via_simulation_driver(void)
     memset(&sim_args, 0, sizeof(sim_args));
     sim_args.replay_path  = r_path;
     sim_args.sim_start_ts = SCHED_SIM_START_TS_LATEST;
-    sim_args.sim_speed    = 0; /* frozen -- deterministic, no wall-clock skew */
 
     memset(&sim, 0, sizeof(sim));
     rc = sched_sim_driver_run(&sim, &sim_args);