Allow consecutive uses of G29

Marlin/src/gcode/bedlevel/abl/G29.cpp

     stepper.synchronize();
 
     // Disable auto bed leveling during G29
-    planner.leveling_active = false;
+    // Be formal so G29 can be done successively without G28.
+    set_bed_leveling_enabled(false);
 
     if (!dryrun) {
       // Re-orient the current position without leveling
     #if HAS_BED_PROBE
       // Deploy the probe. Probe will raise if needed.
       if (DEPLOY_PROBE()) {
-        planner.leveling_active = abl_should_enable;
+        set_bed_leveling_enabled(abl_should_enable);
         return;
       }
     #endif
         || left_probe_bed_position != bilinear_start[X_AXIS]
         || front_probe_bed_position != bilinear_start[Y_AXIS]
       ) {
-        if (dryrun) {
-          // Before reset bed level, re-enable to correct the position
-          planner.leveling_active = abl_should_enable;
-        }
         // Reset grid to 0.0 or "not probed". (Also disables ABL)
         reset_bed_level();
 
       #if HAS_SOFTWARE_ENDSTOPS
         soft_endstops_enabled = enable_soft_endstops;
       #endif
-      planner.leveling_active = abl_should_enable;
+      set_bed_leveling_enabled(abl_should_enable);
       g29_in_progress = false;
       #if ENABLED(LCD_BED_LEVELING)
         lcd_wait_for_move = false;
           measured_z = faux ? 0.001 * random(-100, 101) : probe_pt(xProbe, yProbe, stow_probe_after_each, verbose_level);
 
           if (isnan(measured_z)) {
-            planner.leveling_active = abl_should_enable;
+            set_bed_leveling_enabled(abl_should_enable);
             break;
           }
 
         yProbe = points[i].y;
         measured_z = faux ? 0.001 * random(-100, 101) : probe_pt(xProbe, yProbe, stow_probe_after_each, verbose_level);
         if (isnan(measured_z)) {
-          planner.leveling_active = abl_should_enable;
+          set_bed_leveling_enabled(abl_should_enable);
           break;
         }
         points[i].z = measured_z;
 
     // Raise to _Z_CLEARANCE_DEPLOY_PROBE. Stow the probe.
     if (STOW_PROBE()) {
-      planner.leveling_active = abl_should_enable;
+      set_bed_leveling_enabled(abl_should_enable);
       measured_z = NAN;
     }
   }