fix(utils,core-flows): subtotal calculation and returns location (#13497)

* fix(utils,core-flows): subtotal calculation and returns location

* changeset

* fix test

* var

* rm extra field from test

* fix original total

* fix partial refunds and pending difference

* fix test

* fix test

* test

* extract to util

* original total and update payment when receive return

* original_subtotal

* default fields

* test

* calculate pending difference

* revert claims test

* pending difference

* creadit line fix

* if

.changeset/rare-colts-warn.md

@@ -0,0 +1,9 @@
+---
+"@medusajs/utils": patch
+"@medusajs/types": patch
+"@medusajs/core-flows": patch
+"@medusajs/order": patch
+"@medusajs/medusa": patch
+---
+
+fix(utils): subtotal calculation discounting returned items