This fixes the discount_ calculation logic and promotion tax inclusiveness calculation (#12960)

* This fixes the discount_ calculation logic

* This fixes the adjustment to be handled as a subtotal value in every calculation and applies the tax inclusive logic on the promotion value itself

* Added some testcases and revoked some changes to improve testing output

* Fixed a test case based on feedback

* Corrected promotion/admin test cases

* Corrected cart/store test case

* Improved cart/store test cases for more robust promotion testing considering tax inclusion flags

* Remove unnessary changes as adjustments now automatically are subtotals and therefore the tax inclusive flag does not need to be applied again

* Remove adjustments->is_tax_inclusive usage everywhere

* Migration script to remove is_tax_inclusive in cart line item adjustment

* Forgot to adjust one more testcase

* Corrections based on fPolic feedback

* Refactored PR to consider feedback from oliver

* Added more testcases for promotion in cart

---------

Co-authored-by: Oli Juhl <59018053+olivermrbl@users.noreply.github.com>

packages/modules/promotion/src/utils/compute-actions/line-items.ts

@@ -103,24 +103,29 @@ function applyPromotionToItems(
     ? 1
     : applicationMethod?.max_quantity!
 
-  let lineItemsTotal = MathBN.convert(0)
+  let lineItemsAmount = MathBN.convert(0)
   if (allocation === ApplicationMethodAllocation.ACROSS) {
-    lineItemsTotal = applicableItems.reduce(
+    lineItemsAmount = applicableItems.reduce(
       (acc, item) =>
         MathBN.sub(
-          MathBN.add(acc, item.subtotal),
+          MathBN.add(
+            acc,
+            promotion.is_tax_inclusive ? item.total : item.subtotal
+          ),
           appliedPromotionsMap.get(item.id) ?? 0
         ),
       MathBN.convert(0)
     )
 
-    if (MathBN.lte(lineItemsTotal, 0)) {
+    if (MathBN.lte(lineItemsAmount, 0)) {
       return computedActions
     }
   }
 
   for (const item of applicableItems) {
-    if (MathBN.lte(item.subtotal, 0)) {
+    if (
+      MathBN.lte(promotion.is_tax_inclusive ? item.total : item.subtotal, 0)
+    ) {
       continue
     }
 
@@ -135,11 +140,12 @@ function applyPromotionToItems(
       {
         value: promotionValue,
         applied_value: appliedPromoValue,
+        is_tax_inclusive: promotion.is_tax_inclusive,
         max_quantity: maxQuantity,
         type: applicationMethod?.type!,
         allocation,
       },
-      lineItemsTotal
+      lineItemsAmount
     )
 
     if (MathBN.lte(amount, 0)) {