fix(tax): Make system provider registration backward compatible (#12441)

* fix(tax): Make provider registration backward compatible

* add tests

integration-tests/http/__tests__/order-edits/order-edits.spec.ts

@@ -58,7 +58,7 @@ medusaIntegrationTestRunner({
         await api.post(
           "/admin/tax-regions",
           {
-            provider_id: "tp_system_system",
+            provider_id: "tp_system",
             country_code: "US",
           },
           adminHeaders