Fix PSU on for PID autotune (#19066)

Marlin/src/module/temperature.cpp

@@ -444,6 +444,7 @@ volatile bool Temperature::raw_temps_ready = false;
       LEDColor color = ONHEATINGSTART();
     #endif
 
+    TERN_(AUTO_POWER_CONTROL, powerManager.power_on());
     TERN_(NO_FAN_SLOWING_IN_PID_TUNING, adaptive_fan_slowing = false);
 
     // PID Tuning loop