Add max_terraform_state_size_bytes to the app settings API

What does this MR do and why?

We introduced a limit to the file/data accepted by the POST /projects/:project_id/terraform/state/:name API in the application_settings table, with the new field called as max_terraform_state_size_bytes. (See !106257 (merged))

Here, the new field is added to the GET /application/settings and PUT /application/settings endpoints.

This should wait for !106269 (merged) to be merged.

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

Screenshots or screen recordings

GET /application/settings

PUT /application/settings

Documentation

How to set up and validate locally

1. Make sure you have a user with admin access to a GitLab instance

2. Create a Personal Access Token for that user, make sure it has the sudo scope

3. Run the following curl requests:

   GET application settings

   curl -k -X GET \
   --header "Authorization: Bearer <your personal access token>" \
   "<gitlab-instance-url>/api/v4/application/settings"

   PUT application settings

   curl \
   "<gitlab-instance-url>/api/v4/application/settings" \
   -ki -X PUT \
   --header "Authorization: Bearer <your personal access token>" \
   --header "Content-Type: application/json" \
   --data "{\"max_terraform_state_size_bytes\":1000}"

MR acceptance checklist

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