Merge remote-tracking branch 'bpodrygajlo/vrtsim-perf-fix' into integration_2026_w26

fix(vrtsim): Reduce OS scheduler pressure caused by vrtsim timing thread (#235)

Increase the usleep to 20 uS to reduce the pressure on the OS scheduler.
This reduces the number of context switches and increases performance.
The value 20uS is approximately half a symbol in mu1 and shouldn't cause
too much extra delay.

Reviewed-by: Robert Schmidt <robert.schmidt@openairinterface.org>

radio/vrtsim/vrtsim.c

@@ -272,7 +272,7 @@ static void *vrtsim_timing_job(void *arg)
       shm_td_iq_channel_produce_samples(vrtsim_state->channel, samples_to_produce);
       last_sample_index = sample_index;
     }
-    usleep(1);
+    usleep(20);
   }
   return 0;
 }