Remove migration import settings from the settings API
🔥 Problem
The application settings:
container_registry_import_created_before
container_registry_import_max_retries
container_registry_import_max_step_duration
container_registry_import_max_tags_count
container_registry_import_start_max_retries
container_registry_import_target_plan
container_registry_pre_import_tags_rate
are settings for the Container Registry migration. See &7316 (closed).
This migration is currently set up to only happen on gitlab.com.
In other words, these settings are not useful for self-managed admins nor they have an impact if they are updated (through a rails console for example).
However, these settings are returned in the relevant API.
🚒 Solution
Remove those settings from the API. We should treat them as internal settings that are not exposed to users.