Drop unused preload from PipelineSerializer

app/serializers/pipeline_serializer.rb

@@ -41,7 +41,6 @@ class PipelineSerializer < BaseSerializer
   def preloaded_relations
     [
       :cancelable_statuses,
-      :latest_statuses_ordered_by_stage,
       :retryable_builds,
       :stages,
       :latest_statuses,

changelogs/unreleased/321788-drop-unused-preload.yml

+---
+title: Drop unused preload from PipelineSerializer
+merge_request: 56988
+author:
+type: performance

spec/serializers/pipeline_serializer_spec.rb

@@ -202,7 +202,7 @@ RSpec.describe PipelineSerializer do
           # Existing numbers are high and require performance optimization
           # Ongoing issue:
           # https://gitlab.com/gitlab-org/gitlab/-/issues/225156
-          expected_queries = Gitlab.ee? ? 85 : 76
+          expected_queries = Gitlab.ee? ? 82 : 76
 
           expect(recorded.count).to be_within(2).of(expected_queries)
           expect(recorded.cached_count).to eq(0)