Stabilize acceptance test: BulkEdit/BulkEditCustomerInformation.spec.ts (major)

Parent epic: #17559

Failing acceptance spec on the next major (Platform), reproducible on PHP **8.2 / 8.4 / 8.5** in Nightly [run 28987958476](https://github.com/shopware/shopware/actions/runs/28987958476) (2026-07-09, `trunk`@`ee03bb09`).

**Spec:** [`BulkEdit/BulkEditCustomerInformation.spec.ts`](https://github.com/shopware/shopware/blob/trunk/tests/acceptance/tests/BulkEdit/BulkEditCustomerInformation.spec.ts) · [Currents result](https://app.currents.dev/instance/09001ffb5fe318dc)

### Failing tests (1)
- `5:1` — As a merchant, I can perform bulk edits on customer information · [Currents](https://app.currents.dev/i/https://app.currents.dev/i/09001ffb5fe318dc/test/535c0e93cf2922c5c644-b631ae884b3ced5c09f3)

### Task
- [ ] Reproduce the failure locally / in CI.
- [ ] Root-cause: broken spec vs. real product regression on major.
- [ ] Fix the spec, or coordinate the fix with the responsible dev team.
- [ ] Confirm the spec passes on major (PHP 8.2 / 8.4 / 8.5).

_Source: Nightly run 28987958476 � Currents run `0182569cf1d33ee7`._