Fix preloading unrelated associations for CommitStatus

In the Ci::DropPipelineService we preloaded relations
that did not exist for commit status. This triggered
and error for customers.

Changelog: fixed

app/services/ci/drop_pipeline_service.rb

@@ -2,6 +2,9 @@
 
 module Ci
   class DropPipelineService
+    PRELOADED_COMMIT_STATUS_RELATIONS = [:project, :pipeline].freeze
+    PRELOADED_CI_BUILD_RELATIONS = [:metadata, :deployment, :taggings].freeze
+
     # execute service asynchronously for each cancelable pipeline
     def execute_async_for_all(pipelines, failure_reason, context_user)
       pipelines.cancelable.select(:id).find_in_batches do |pipelines_batch|
@@ -27,11 +30,11 @@ module Ci
 
     private
 
-    def preload_associations_for_drop(builds_batch)
-      ActiveRecord::Associations::Preloader.new.preload( # rubocop: disable CodeReuse/ActiveRecord
-        builds_batch,
-        [:project, :pipeline, :metadata, :deployment, :taggings]
-      )
+    # rubocop: disable CodeReuse/ActiveRecord
+    def preload_associations_for_drop(commit_status_batch)
+      ActiveRecord::Associations::Preloader.new.preload(commit_status_batch, PRELOADED_COMMIT_STATUS_RELATIONS)
+      ActiveRecord::Associations::Preloader.new.preload(commit_status_batch.select { |job| job.is_a?(Ci::Build) }, PRELOADED_CI_BUILD_RELATIONS)
     end
+    # rubocop: enable CodeReuse/ActiveRecord
   end
 end

spec/services/ci/drop_pipeline_service_spec.rb

@@ -9,8 +9,10 @@ RSpec.describe Ci::DropPipelineService do
 
   let!(:cancelable_pipeline) { create(:ci_pipeline, :running, user: user) }
   let!(:running_build) { create(:ci_build, :running, pipeline: cancelable_pipeline) }
+  let!(:commit_status_running) { create(:commit_status, :running, pipeline: cancelable_pipeline) }
   let!(:success_pipeline) { create(:ci_pipeline, :success, user: user) }
   let!(:success_build) { create(:ci_build, :success, pipeline: success_pipeline) }
+  let!(:commit_status_success) { create(:commit_status, :success, pipeline: cancelable_pipeline) }
 
   describe '#execute_async_for_all' do
     subject { described_class.new.execute_async_for_all(user.pipelines, failure_reason, user) }