Use MembersFinder ancestors linear scopes

In this commit we're replacing the recursive ancestors scope in
the `MembersFinder` class, for their linear version.

Changelog: performance

app/finders/members_finder.rb

@@ -70,11 +70,16 @@ class MembersFinder
   end
 
   def project_invited_groups
-    invited_groups_ids_including_ancestors = Gitlab::ObjectHierarchy
+    invited_groups_and_ancestors = if ::Feature.enabled?(:linear_members_finder_ancestor_scopes, current_user, default_enabled: :yaml)
+                                     project.invited_groups
+                                       .self_and_ancestors
+                                   else
+                                     Gitlab::ObjectHierarchy
                                        .new(project.invited_groups)
                                        .base_and_ancestors
-      .public_or_visible_to_user(current_user)
-      .select(:id)
+                                   end
+
+    invited_groups_ids_including_ancestors = invited_groups_and_ancestors.public_or_visible_to_user(current_user).select(:id)
 
     GroupMember.with_source_id(invited_groups_ids_including_ancestors).non_minimal_access
   end

config/feature_flags/development/linear_members_finder_ancestor_scopes.yml

+---
+name: linear_members_finder_ancestor_scopes
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/70583
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/341347
+milestone: '14.4'
+type: development
+group: group::access
+default_enabled: false

spec/finders/members_finder_spec.rb

@@ -161,6 +161,7 @@ RSpec.describe MembersFinder, '#execute' do
   end
 
   context 'when :invited_groups is passed' do
+    shared_examples 'with invited_groups param' do
       subject { described_class.new(project, user2).execute(include_relations: [:inherited, :direct, :invited_groups]) }
 
       let_it_be(:linked_group) { create(:group, :public) }
@@ -199,4 +200,15 @@ RSpec.describe MembersFinder, '#execute' do
         end
       end
     end
+
+    it_behaves_like 'with invited_groups param'
+
+    context 'when feature flag :linear_members_finder_ancestor_scopes is disabled' do
+      before do
+        stub_feature_flags(linear_members_finder_ancestor_scopes: false)
+      end
+
+      it_behaves_like 'with invited_groups param'
+    end
+  end
 end