fix: Unique constraint should account for soft deleted records (#11048)

FIXES FRMW-2878

**What**
Currently, the `one-to-one` unique constraints does not account for deleted record. This prevents from inserting a new record wth the same fk if another one is deleted.

**Caveat**
`hasOne` with FK option is meant to be a special case, for example a many to one - one to many without defining the other side of the relation. In that case we don't handle this behaviour and keep it as it is

packages/modules/cart/src/migrations/.snapshot-medusa-cart.json

@@ -309,24 +309,6 @@
       "name": "cart",
       "schema": "public",
       "indexes": [
-        {
-          "columnNames": [
-            "shipping_address_id"
-          ],
-          "composite": false,
-          "keyName": "cart_shipping_address_id_unique",
-          "primary": false,
-          "unique": true
-        },
-        {
-          "columnNames": [
-            "billing_address_id"
-          ],
-          "composite": false,
-          "keyName": "cart_billing_address_id_unique",
-          "primary": false,
-          "unique": true
-        },
         {
           "keyName": "IDX_cart_deleted_at",
           "columnNames": [],

packages/modules/cart/src/migrations/Migration20250120115059.ts

@@ -0,0 +1,21 @@
+import { Migration } from "@mikro-orm/migrations"
+
+export class Migration20250120115059 extends Migration {
+  async up(): Promise<void> {
+    this.addSql(
+      'alter table if exists "cart" drop constraint if exists "cart_shipping_address_id_unique";'
+    )
+    this.addSql(
+      'alter table if exists "cart" drop constraint if exists "cart_billing_address_id_unique";'
+    )
+  }
+
+  async down(): Promise<void> {
+    this.addSql(
+      'alter table if exists "cart" add constraint "cart_shipping_address_id_unique" unique ("shipping_address_id");'
+    )
+    this.addSql(
+      'alter table if exists "cart" add constraint "cart_billing_address_id_unique" unique ("billing_address_id");'
+    )
+  }
+}