Remove legacy Sprint model

[ulferts]

Ticket

https://community.openproject.org/wp/71254

What are you trying to accomplish?

• Remove legacy sprint.rb
• Move agile/sprint.rb to sprint.rb
• Move agile/backlog_bucket.rb to backlog_bucket.rb
• Remove version_settings.rb
  • Migration referencing the model is still usable.
•  removes backlog.rb
  • The scope inbox_for in it is moved to WorkPackage
• story.rb, task.rb and prevent_issue_sti.rb removed
• issue_spec.rb is merged into work_package_spec.rb. Superfluous done? method is removed.
• Rework work_package_journal_on_burndown_attributes index which should be used by burndown but was using version_id instead of sprint_id

Merge checklist

• Added/updated tests
• Added/updated documentation in Lookbook (patterns, previews, etc)
• Tested major browsers (Chrome, Firefox, Edge, ...)

[EinLama]

#22706 introduces a patch to the resource link generator that we might be able to remove here, when the sprint model changes its name 👀

[ulferts]

The failing spec fails on dev as well.

[ulferts]

The failing rspec ./modules/team_planner/spec/features/team_planner_context_menu_spec.rb:41 is flickering.

[dombesz]

Nice work👍

[dombesz]

Is this key being used anywhere?

[ulferts]

It will be used in the unlikely case that the Backlogs::BacklogSettingsContract adds an error to sprint_sharing

[dombesz]

Nice catch👏

[ulferts]

The failing spec

rspec ./spec/features/work_packages/details/inplace_editor/subject_editor_spec.rb:33

Is a spec known to flicker. The spec is green locally.