Remove Group > Settings > Project
## Problem
In https://gitlab.com/gitlab-org/gitlab/-/issues/456434 we have implemented a URL redirect in preparation to remove Groups > Settings > Projects. In this issue, the page should be removed entirely.
Page to be removed:

Page we re-directed to:

## Proposal
- [ ] Remove the navigation element `Projects` in group settings
- [ ] Ensure that a 404 page not found error is thrown when accessing the URL
References:
- https://handbook.gitlab.com/handbook/marketing/blog/release-posts/#deprecations-and-other-planned-breaking-change-announcements
- https://docs.gitlab.com/ee/development/deprecation_guidelines/
## Implementation guide
- In [config/routes/group.rb#L16](https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/routes/group.rb#L16) remove `get 'projects', to: redirect('groups/%{id}')`
- In [lib/sidebars/groups/menus/settings_menu.rb#L75](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/sidebars/groups/menus/settings_menu.rb#L75) remove `Projects` menu item
- Remove [app/views/groups/projects.html.haml](https://gitlab.com/gitlab-org/gitlab/-/blob/master/app/views/groups/projects.html.haml)
- Remove [app/controllers/groups_controller.rb#L149](https://gitlab.com/gitlab-org/gitlab/-/blob/master/app/controllers/groups_controller.rb#L149)
issue