Advanced Search: Enable group level optimization

ee/config/feature_flags/development/elasticsearch_use_group_level_optimization.yml

----
-name: elasticsearch_use_group_level_optimization
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/69741
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/340596
-milestone: '14.4'
-type: development
-group: group::global search
-default_enabled: false

ee/lib/elastic/latest/issue_class_proxy.rb

@@ -60,7 +60,6 @@ module Elastic
       def should_use_project_ids_filter?(options)
         options[:project_ids] == :any ||
         options[:group_ids].blank? ||
-        Feature.disabled?(:elasticsearch_use_group_level_optimization) ||
         !Elastic::DataMigrationService.migration_has_finished?(:redo_backfill_namespace_ancestry_ids_for_issues)
       end
 

ee/spec/services/search/group_service_spec.rb

@@ -206,24 +206,8 @@ RSpec.describe Search::GroupService do
         permission_table_for_guest_feature_access
       end
 
-      context 'elasticsearch_use_group_level_optimization is enabled' do
-        before do
-          stub_feature_flags(elasticsearch_use_group_level_optimization: true)
-        end
-
-        with_them do
-          it_behaves_like 'search respects visibility'
-        end
-      end
-
-      context 'elasticsearch_use_group_level_optimization is disabled' do
-        before do
-          stub_feature_flags(elasticsearch_use_group_level_optimization: false)
-        end
-
-        with_them do
-          it_behaves_like 'search respects visibility'
-        end
+      with_them do
+        it_behaves_like 'search respects visibility'
       end
     end
 
@@ -319,21 +303,7 @@ RSpec.describe Search::GroupService do
         ensure_elasticsearch_index!
       end
 
-      context 'elasticsearch_use_group_level_optimization is enabled' do
-        before do
-          stub_feature_flags(elasticsearch_use_group_level_optimization: true)
-        end
-
-        include_examples 'search results sorted'
-      end
-
-      context 'elasticsearch_use_group_level_optimization is disabled' do
-        before do
-          stub_feature_flags(elasticsearch_use_group_level_optimization: false)
-        end
-
-        include_examples 'search results sorted'
-      end
+      include_examples 'search results sorted'
     end
 
     context 'merge requests' do