Use scope for issue search preloads

ee/changelogs/unreleased/ali-refactor-api-search-issue-preloads.yml

+---
+title: Improve performance of Advanced Search API (Issues scope) by preloading more associations
+merge_request: 30778
+author:
+type: performance

ee/spec/requests/api/search_spec.rb

@@ -160,19 +160,21 @@ describe API::Search do
 
     context 'for issues scope', :sidekiq_inline do
       before do
-        create_list(:issue, 4, project: project)
+        create_list(:issue, 2, project: project)
         ensure_elasticsearch_index!
       end
 
       it 'avoids N+1 queries' do
         control = ActiveRecord::QueryRecorder.new { get api(endpoint, user), params: { scope: 'issues', search: '*' } }
 
-        new_issues = create_list(:issue, 4, project: project)
+        create_list(:issue, 2, project: project)
+        create_list(:issue, 2, project: create(:project, group: group))
+        create_list(:issue, 2)
 
         ensure_elasticsearch_index!
 
         # Some N+1 queries still exist
-        expect { get api(endpoint, user), params: { scope: 'issues', search: '*' } }.not_to exceed_query_limit(control.count + new_issues.count * 4)
+        expect { get api(endpoint, user), params: { scope: 'issues', search: '*' } }.not_to exceed_query_limit(control.count + 2)
       end
 
       it_behaves_like 'pagination', scope: 'issues'

lib/api/search.rb

@@ -21,8 +21,9 @@ module API
       }.freeze
 
       SCOPE_PRELOAD_METHOD = {
-          merge_requests: :with_api_entity_associations,
-          projects: :with_api_entity_associations
+        merge_requests: :with_api_entity_associations,
+        projects: :with_api_entity_associations,
+        issues: :with_api_entity_associations
       }.freeze
 
       def search(additional_params = {})