Better RESTORE_LEVELING_AFTER_G28 sanity-check

As suggested by @GMagician

Marlin/src/inc/SanityCheck.h

@@ -835,8 +835,8 @@ static_assert(X_MAX_LENGTH >= X_BED_SIZE && Y_MAX_LENGTH >= Y_BED_SIZE,
     #error "AUTO_BED_LEVELING_UBL requires EEPROM_SETTINGS. Please update your configuration."
   #elif !WITHIN(GRID_MAX_POINTS_X, 3, 15) || !WITHIN(GRID_MAX_POINTS_Y, 3, 15)
     #error "GRID_MAX_POINTS_[XY] must be a whole number between 3 and 15."
-  #elif DISABLED(RESTORE_LEVELING_AFTER_G28)
-    #error "AUTO_BED_LEVELING_UBL (<=1.1.8) always has RESTORE_LEVELING_AFTER_G28 enabled. To keep this behavior, #define RESTORE_LEVELING_AFTER_G28. To keep it disabled comment out this line in SanityCheck.h."
+  #elif !defined(RESTORE_LEVELING_AFTER_G28)
+    #error "AUTO_BED_LEVELING_UBL used to enable RESTORE_LEVELING_AFTER_G28. To keep this behavior enable RESTORE_LEVELING_AFTER_G28. Otherwise define it as 'false'."
   #endif
 
 #elif OLDSCHOOL_ABL