Redirect to epics when work item is not available

app/controllers/groups/work_items_controller.rb

app/controllers/groups_controller.rb

app/finders/work_items/work_items_finder.rb

app/graphql/resolvers/namespaces/work_item_resolver.rb

app/graphql/resolvers/namespaces/work_items_resolver.rb

app/models/group.rb

app/services/groups/autocomplete_service.rb

ee/app/controllers/ee/groups/work_items_controller.rb

ee/app/controllers/groups/epics_controller.rb

ee/app/helpers/ee/nav/new_dropdown_helper.rb

ee/app/models/ee/group.rb

ee/spec/controllers/groups/epics_controller_spec.rb

...c/features/discussion_comments/epic_quick_actions_spec.rb

ee/spec/features/discussion_comments/epic_spec.rb

ee/spec/features/epics/abuse_report_spec.rb

ee/spec/features/epics/confidential_notes_spec.rb

ee/spec/features/epics/epic_issues_spec.rb

ee/spec/features/epics/epic_labels_spec.rb

ee/spec/features/epics/epic_related_epics_spec.rb

ee/spec/features/epics/epic_show_spec.rb