Use linear version GroupsWithTemplatesFinder#extended_group_search

config/feature_flags/development/linear_groups_template_finder_extended_group_search_ancestors_scopes.yml

+---
+name: linear_groups_template_finder_extended_group_search_ancestors_scopes
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/74599
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/345786
+milestone: '14.6'
+type: development
+group: group::access
+default_enabled: false

ee/app/finders/groups_with_templates_finder.rb

@@ -18,11 +18,15 @@ class GroupsWithTemplatesFinder
   attr_reader :group_id
 
   def extended_group_search
-    groups = Group.with_project_templates
-    groups_with_plan = Gitlab::ObjectHierarchy
-      .new(groups)
+    groups = if Feature.enabled?(:linear_groups_template_finder_extended_group_search_ancestors_scopes, current_group, default_enabled: :yaml)
+               Group.with_project_templates.self_and_ancestors
+             else
+               Gitlab::ObjectHierarchy
+                 .new(Group.with_project_templates)
                  .base_and_ancestors
-      .with_feature_available_in_plan(:group_project_templates)
+             end
+
+    groups_with_plan = groups.with_feature_available_in_plan(:group_project_templates)
 
     # We're adding an extra query that will be removed once we remove the feature flag in https://gitlab.com/gitlab-org/gitlab/-/issues/339439
     if ::Feature.enabled?(:linear_groups_template_finder_extended_group_search, current_group, default_enabled: :yaml)

ee/spec/finders/groups_with_templates_finder_spec.rb

@@ -106,4 +106,21 @@ RSpec.describe GroupsWithTemplatesFinder, :saas do
 
     it_behaves_like 'group template finder examples'
   end
+
+  context 'when feature flag :linear_groups_template_finder_extended_group_search_ancestors_scopes is disabled' do
+    before do
+      stub_feature_flags(linear_groups_template_finder_extended_group_search_ancestors_scopes: false)
+    end
+
+    it_behaves_like 'group template finder examples'
+  end
+
+  context 'when all linear feature flags are disabled' do
+    before do
+      stub_feature_flags(linear_groups_template_finder_extended_group_search: false)
+      stub_feature_flags(linear_groups_template_finder_extended_group_search_ancestors_scopes: false)
+    end
+
+    it_behaves_like 'group template finder examples'
+  end
 end