Allow Z_AFTER_PROBING to be 0

Marlin/src/feature/bedlevel/ubl/ubl_G29.cpp

 
       STOW_PROBE();
 
-      #if Z_AFTER_PROBING
+      #ifdef Z_AFTER_PROBING
         move_z_after_probing();
       #endif
 

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

   if (planner.leveling_active)
     SYNC_PLAN_POSITION_KINEMATIC();
 
-  #if HAS_BED_PROBE && Z_AFTER_PROBING
+  #if HAS_BED_PROBE && defined(Z_AFTER_PROBING)
     move_z_after_probing();
   #endif
 

Marlin/src/gcode/calibrate/G28.cpp

           HOMEAXIS(Z);
         #endif
 
-        #if HOMING_Z_WITH_PROBE && Z_AFTER_PROBING
+        #if HOMING_Z_WITH_PROBE && defined(Z_AFTER_PROBING)
           move_z_after_probing();
         #endif
 

Marlin/src/gcode/probe/G30.cpp

 
   clean_up_after_endstop_or_probe_move();
 
-  #if Z_AFTER_PROBING
+  #ifdef Z_AFTER_PROBING
     if (raise_after == PROBE_PT_STOW) move_z_after_probing();
   #endif
 

Marlin/src/gcode/probe/M401_M402.cpp

  */
 void GcodeSuite::M402() {
   STOW_PROBE();
-  #if Z_AFTER_PROBING
+  #ifdef Z_AFTER_PROBING
     move_z_after_probing();
   #endif
   report_current_position();

Marlin/src/module/probe.cpp

   return false;
 }
 
-#if Z_AFTER_PROBING
+#ifdef Z_AFTER_PROBING
   // After probing move to a preferred Z position
   void move_z_after_probing() {
     if (current_position[Z_AXIS] != Z_AFTER_PROBING) {

Marlin/src/module/probe.h

 #if HAS_BED_PROBE
   extern float zprobe_zoffset;
   bool set_probe_deployed(const bool deploy);
-  #if Z_AFTER_PROBING
+  #ifdef Z_AFTER_PROBING
     void move_z_after_probing();
   #endif
   enum ProbePtRaise : unsigned char {