Apply HAS_MULTI_HOTEND

Marlin/src/inc/Conditionals_LCD.h

   #ifndef HOTEND_OVERSHOOT
     #define HOTEND_OVERSHOOT 15
   #endif
-  #if HOTENDS_ > 1
+  #if HOTENDS > 1
     #define HAS_MULTI_HOTEND 1
     #define HAS_HOTEND_OFFSET 1
   #endif

Marlin/src/inc/Conditionals_post.h

 #if HAS_HOTEND && PIN_EXISTS(E0_AUTO_FAN)
   #define HAS_AUTO_FAN_0 1
 #endif
-#if HOTENDS > 1 && PIN_EXISTS(E1_AUTO_FAN)
+#if HAS_MULTI_HOTEND && PIN_EXISTS(E1_AUTO_FAN)
   #define HAS_AUTO_FAN_1 1
 #endif
 #if HOTENDS > 2 && PIN_EXISTS(E2_AUTO_FAN)
  */
 
 #define WRITE_HEATER_0P(v) WRITE(HEATER_0_PIN, (v) ^ HEATER_0_INVERTING)
-#if HOTENDS > 1 || ENABLED(HEATERS_PARALLEL)
+#if EITHER(HAS_MULTI_HOTEND, HEATERS_PARALLEL)
   #define WRITE_HEATER_1(v) WRITE(HEATER_1_PIN, (v) ^ HEATER_1_INVERTING)
   #if HOTENDS > 2
     #define WRITE_HEATER_2(v) WRITE(HEATER_2_PIN, (v) ^ HEATER_2_INVERTING)
       #endif // HOTENDS > 4
     #endif // HOTENDS > 3
   #endif // HOTENDS > 2
-#endif // HOTENDS > 1
+#endif // HAS_MULTI_HOTEND || HEATERS_PARALLEL
 #if ENABLED(HEATERS_PARALLEL)
   #define WRITE_HEATER_0(v) { WRITE_HEATER_0P(v); WRITE_HEATER_1(v); }
 #else

Marlin/src/module/tool_change.cpp

     #endif
 
     // Migrate the temperature to the new hotend
-    #if HOTENDS > 1
+    #if HAS_MULTI_HOTEND
       thermalManager.setTargetHotend(thermalManager.degTargetHotend(active_extruder), migration_extruder);
       #if HAS_DISPLAY
         thermalManager.set_heating_message(0);