Adjust locator in billing test and add data-test attribute

Updated the locator for the 'manageBillingButton' in the end-to-end billing test. Instead of an id, the locator now targets a data property. This change was also reflected in the Button component within 'billing-portal-card.tsx' where the attribute data-test was added for test recognition.

apps/e2e/tests/utils/billing.po.ts

@@ -21,7 +21,7 @@ export class BillingPageObject {
   }
 
   manageBillingButton() {
-    return this.page.locator('manage-billing-redirect-button');
+    return this.page.locator('[data-test="manage-billing-redirect-button"]');
   }
 
   successStatus() {