Fix LCD issue on stepper timeout (#13630)

- Remove a re-paint of the status screen on stepper timeout, which would cause a garbled LCD with `LIGHTWEIGHT_UI` and could interrupt whatever else the user might be doing in a submenu (such as playing games!)
- Use the helper function to reset stepper timeout.

Marlin/src/Marlin.cpp

@@ -457,7 +457,7 @@ void manage_inactivity(const bool ignore_stepper_queue/*=false*/) {
   if (stepper_inactive_time) {
     static bool already_shutdown_steppers; // = false
     if (planner.has_blocks_queued())
-      gcode.previous_move_ms = ms; // reset_stepper_timeout to keep steppers powered
+      gcode.reset_stepper_timeout();
     else if (MOVE_AWAY_TEST && !ignore_stepper_queue && ELAPSED(ms, gcode.previous_move_ms + stepper_inactive_time)) {
       if (!already_shutdown_steppers) {
         already_shutdown_steppers = true;  // L6470 SPI will consume 99% of free time without this
@@ -473,14 +473,11 @@ void manage_inactivity(const bool ignore_stepper_queue/*=false*/) {
         #if ENABLED(DISABLE_INACTIVE_E)
           disable_e_steppers();
         #endif
-        #if HAS_LCD_MENU
-          ui.status_screen();
-          #if ENABLED(AUTO_BED_LEVELING_UBL)
-            if (ubl.lcd_map_control) {
-              ubl.lcd_map_control = false;
-              ui.defer_status_screen(false);
-            }
-          #endif
+        #if HAS_LCD_MENU && ENABLED(AUTO_BED_LEVELING_UBL)
+          if (ubl.lcd_map_control) {
+            ubl.lcd_map_control = false;
+            ui.defer_status_screen(false);
+          }
         #endif
       }
     }
@@ -617,7 +614,7 @@ void manage_inactivity(const bool ignore_stepper_queue/*=false*/) {
         }
       #endif // !SWITCHING_EXTRUDER
 
-      gcode.previous_move_ms = ms; // reset_stepper_timeout to keep steppers powered
+      gcode.reset_stepper_timeout();
     }
   #endif // EXTRUDER_RUNOUT_PREVENT