Enable linear GroupPlanPreloader ancestors queries

In this commit, we're removing the feature flag
`linear_group_plans_preloaded_ancestor_scopes` to allow
GroupPlanPreloader using linear queries.

Changelog: added
EE: true

config/feature_flags/development/linear_group_plans_preloaded_ancestor_scopes.yml

----
-name: linear_group_plans_preloaded_ancestor_scopes
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/70685
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/341349
-milestone: '14.4'
-type: development
-group: group::access
-default_enabled: false

ee/lib/gitlab/group_plans_preloader.rb

@@ -57,17 +57,10 @@ module Gitlab
     # Returns an ActiveRecord::Relation that includes the given groups, and all
     # their (recursive) ancestors.
     def groups_and_ancestors_for(groups)
-      groups_and_ancestors = if ::Feature.enabled?(:linear_group_plans_preloaded_ancestor_scopes, default_enabled: :yaml)
-                               groups.self_and_ancestors
-                             else
-                               Gitlab::ObjectHierarchy
-                                 .new(groups)
-                                 .base_and_ancestors
-                             end
-
-      groups_and_ancestors
-        .join_gitlab_subscription
-        .select('namespaces.id', 'namespaces.parent_id', 'gitlab_subscriptions.hosted_plan_id')
+      groups
+       .self_and_ancestors
+       .join_gitlab_subscription
+       .select('namespaces.id', 'namespaces.parent_id', 'gitlab_subscriptions.hosted_plan_id')
     end
   end
 end

ee/spec/lib/gitlab/group_plans_preloader_spec.rb

@@ -52,13 +52,5 @@ RSpec.describe Gitlab::GroupPlansPreloader, :saas do
     end
 
     it_behaves_like 'preloading cases'
-
-    context 'when feature flag :linear_group_plans_preloaded_ancestor_scopes is disabled' do
-      before do
-        stub_feature_flags(linear_group_plans_preloaded_ancestor_scopes: false)
-      end
-
-      it_behaves_like 'preloading cases'
-    end
   end
 end

ee/spec/requests/api/graphql/mutations/boards/issues/issue_move_list_spec.rb

@@ -5,10 +5,21 @@ require 'spec_helper'
 RSpec.describe 'Reposition and move issue within board lists' do
   include GraphqlHelpers
 
-  let_it_be(:group) { create(:group, :private) }
-  let_it_be(:project) { create(:project, group: group) }
-  let_it_be(:board) { create(:board, group: group) }
   let_it_be(:user) { create(:user) }
+
+  let_it_be(:group) do
+    create(:group, :private).tap do |g|
+      g.add_guest(user)
+    end
+  end
+
+  let_it_be(:project) do
+    create(:project, group: group).tap do |p|
+      p.add_reporter(user)
+    end
+  end
+
+  let_it_be(:board) { create(:board, group: group) }
   let_it_be(:epic) { create(:epic, group: group) }
   let_it_be(:existing_issue1) { create(:labeled_issue, project: project, relative_position: 10) }
   let_it_be(:existing_issue2) { create(:labeled_issue, project: project, relative_position: 50) }
@@ -36,15 +47,7 @@ RSpec.describe 'Reposition and move issue within board lists' do
   end
 
   context 'when user can admin issue' do
-    before do
-      project.add_reporter(user)
-    end
-
     context 'when user can read epic' do
-      before do
-        group.add_guest(user)
-      end
-
       it 'updates issue position and epic' do
         post_graphql_mutation(mutation(params), current_user: user)