Allow new Direct Transfer batch limit setting to be set via admin UI
<!--IssueSummary start-->
<details>
<summary>
Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards.
</summary>
- [Work on this issue](https://contributors.gitlab.com/manage-issue?action=work&projectId=278964&issueIid=434910)
- [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=434910)
</details>
<!--IssueSummary end-->
This issue came from this discussion https://gitlab.com/gitlab-org/gitlab/-/merge_requests/136018#note_1643599722).
We added a new application setting in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/136018 and should expose it in the admin UI.
issue