Add Terraform state size limit to admin UI

What does this MR do and why?

Adds a "Terraform limits" section to admin -> settings -> preferences, with a field for the new max_terraform_state_size_bytes setting.

Note: must be merged after !106269 (merged), otherwise changing the setting will have no effect.

Screenshots or screen recordings

How to set up and validate locally

1. Vist /admin/application_settings/preferences
2. Expand "Terraform limits" and update the max file size setting

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

https://gitlab.com/gitlab-org/gitlab/-/issues/352951