Fix(medusa-test-utils): config loader (#6919)

packages/currency/src/joiner-config.ts

@@ -5,6 +5,8 @@ import Currency from "./models/currency"
 
 export const LinkableKeys: Record<string, string> = {
   code: Currency.name,
+  currency_code: Currency.name,
+  default_currency_code: Currency.name,
 }
 
 const entityLinkableKeysMap: MapToConfig = {}