Preload build report results for pipeline builds

It fixes N + 1 issue

app/serializers/pipeline_serializer.rb

@@ -42,6 +42,7 @@ class PipelineSerializer < BaseSerializer
     [
       :cancelable_statuses,
       :latest_statuses_ordered_by_stage,
+      :latest_builds_report_results,
       :manual_actions,
       :retryable_builds,
       :scheduled_actions,

changelogs/unreleased/id-preload-pipeline-reports.yml

+---
+title: Preload build report results for pipeline builds
+merge_request: 37582
+author:
+type: performance

spec/serializers/pipeline_serializer_spec.rb

@@ -231,7 +231,7 @@ RSpec.describe PipelineSerializer do
           # :source_pipeline and :source_job
           # Existing numbers are high and require performance optimization
           # https://gitlab.com/gitlab-org/gitlab/-/issues/225156
-          expected_queries = Gitlab.ee? ? 101 : 92
+          expected_queries = Gitlab.ee? ? 95 : 86
 
           expect(recorded.count).to be_within(2).of(expected_queries)
           expect(recorded.cached_count).to eq(0)