Fix specs creating a pipeline stage with implicit index

spec/factories/commit_statuses.rb

@@ -2,6 +2,7 @@ FactoryBot.define do
   factory :commit_status, class: CommitStatus do
     name 'default'
     stage 'test'
+    stage_idx 0
     status 'success'
     description 'commit status'
     pipeline factory: :ci_pipeline_with_one_job

spec/lib/gitlab/ci/pipeline/chain/create_spec.rb

@@ -17,7 +17,7 @@ describe Gitlab::Ci::Pipeline::Chain::Create do
 
   context 'when pipeline is ready to be saved' do
     before do
-      pipeline.stages.build(name: 'test', project: project)
+      pipeline.stages.build(name: 'test', index: 0, project: project)
 
       step.perform!
     end

spec/services/ci/retry_build_service_spec.rb

@@ -6,7 +6,9 @@ describe Ci::RetryBuildService do
   set(:pipeline) { create(:ci_pipeline, project: project) }
 
   let(:stage) do
-    Ci::Stage.create!(project: project, pipeline: pipeline, name: 'test')
+    create(:ci_stage_entity, project: project,
+                             pipeline: pipeline,
+                             name: 'test')
   end
 
   let(:build) { create(:ci_build, pipeline: pipeline, stage_id: stage.id) }