Use created_at_desc as the default sorting option for Group Lists

What does this MR do and why?

Use created_at_desc as the default sorting option for all group lists.

• Decouples the group list's initial sort value from the project's preferred sorting field
• Prevents having updated_at as the initial sorting column, which carries over from the project's preferred sorting field.
  • There is no database index for updated_at, sorting by it is sub-optimal. See #585432 (comment 3056785268) for reference.
  • Adding the proper index to support sorting by updated_at requires separate effort #588691

References

• Related to #588987 (closed)
• #585432 (comment 3056785268)
• https://gitlab.com/gitlab-org/database-team/team-tasks/-/issues/580#note_3063112249

Screenshots or screen recordings

How to set up and validate locally

1. Enable the explore_groups_vue feature flag in /rails/features
2. Go to any of the page:
   • http://localhost:3000/dashboard/groups
   • http://localhost:3000/admin/groups
   • http://localhost:3000/explore/groups
   • http://localhost:3000/gitlab-org

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.