Allow increased diff file limits in merge requests with configurable pagination
<!--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>
- [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=418839)
</details>
<!--IssueSummary end-->
### Proposal
An ultimate customer is migrating a codebase to GitLab and has Merge Requests that contain more than 3000 diff files. They would like the ability to increase the diff file limit in merge requests > 3000 per project, and configure UI pagination up to that limit.
Related issues: [!23328](https://gitlab.com/gitlab-org/gitlab/-/issues/23328), [!332194](https://gitlab.com/gitlab-org/gitlab/-/issues/332194), and [!241185](https://gitlab.com/gitlab-org/gitlab/-/issues/241185).
issue