Backport attached merge request pipelines

Backport changes to CE

app/services/merge_requests/base_service.rb

@@ -55,15 +55,7 @@ module MergeRequests
     end
 
     def create_pipeline_for(merge_request, user)
-      return unless Feature.enabled?(:ci_merge_request_pipeline,
-                                     merge_request.source_project,
-                                     default_enabled: true)
-
-      ##
-      # UpdateMergeRequestsWorker could be retried by an exception.
-      # MR pipelines should not be recreated in such case.
-      return if merge_request.merge_request_pipeline_exists?
-      return if merge_request.has_no_commits?
+      return unless can_create_pipeline_for?(merge_request)
 
       create_detached_merge_request_pipeline(merge_request, user)
     end
@@ -80,6 +72,16 @@ module MergeRequests
       end
     end
 
+    def can_create_pipeline_for?(merge_request)
+      ##
+      # UpdateMergeRequestsWorker could be retried by an exception.
+      # pipelines for merge request should not be recreated in such case.
+      return false if merge_request.merge_request_pipeline_exists?
+      return false if merge_request.has_no_commits?
+
+      true
+    end
+
     def can_use_merge_request_ref?(merge_request)
       Feature.enabled?(:ci_use_merge_request_ref, project, default_enabled: true) &&
         !merge_request.for_fork?

spec/services/merge_requests/create_service_spec.rb

@@ -263,19 +263,6 @@ describe MergeRequests::CreateService do
               expect(merge_request.actual_head_pipeline).to be_merge_request_event
             end
           end
-
-          context "when the 'ci_merge_request_pipeline' feature flag is disabled" do
-            before do
-              stub_feature_flags(ci_merge_request_pipeline: false)
-            end
-
-            it 'does not create a detached merge request pipeline' do
-              expect(merge_request).to be_persisted
-
-              merge_request.reload
-              expect(merge_request.merge_request_pipelines.count).to eq(0)
-            end
-          end
         end
 
         context "when .gitlab-ci.yml does not have merge_requests keywords" do

spec/services/merge_requests/refresh_service_spec.rb

@@ -230,17 +230,6 @@ describe MergeRequests::RefreshService do
             end.not_to change { @merge_request.merge_request_pipelines.count }
           end
         end
-
-        context "when the 'ci_merge_request_pipeline' feature flag is disabled" do
-          before do
-            stub_feature_flags(ci_merge_request_pipeline: false)
-          end
-
-          it 'does not create a detached merge request pipeline' do
-            expect { subject }
-              .not_to change { @merge_request.merge_request_pipelines.count }
-          end
-        end
       end
 
       context "when .gitlab-ci.yml does not have merge_requests keywords" do