User linear version UserGroupNotificationSettingsFinder#execute

In this commit we're removing the ff
`linear_user_group_notification_settings_finder_ancestors_scopes` and
enabling the linear version of
`UserGroupNotificationSettingsFinder#execute`.

Changelog: changed

app/finders/user_group_notification_settings_finder.rb

@@ -7,15 +7,7 @@ class UserGroupNotificationSettingsFinder
   end
 
   def execute
-    # rubocop: disable CodeReuse/ActiveRecord
-    selected_groups = Group.where(id: groups.select(:id))
-    groups_with_ancestors = if Feature.enabled?(:linear_user_group_notification_settings_finder_ancestors_scopes, user, default_enabled: :yaml)
-                              selected_groups.self_and_ancestors
-                            else
-                              Gitlab::ObjectHierarchy.new(selected_groups).base_and_ancestors
-                            end
-    # rubocop: enable CodeReuse/ActiveRecord
-
+    groups_with_ancestors = groups.self_and_ancestors
     @loaded_groups_with_ancestors = groups_with_ancestors.index_by(&:id)
     @loaded_notification_settings = user.notification_settings_for_groups(groups_with_ancestors).preload_source_route.index_by(&:source_id)
 

config/feature_flags/development/linear_user_group_notification_settings_finder_ancestors_scopes.yml

----
-name: linear_user_group_notification_settings_finder_ancestors_scopes
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/74606
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/345792
-milestone: '14.6'
-type: development
-group: group::access
-default_enabled: false