Remove merge_base_pipelines feature flag

Remove the existing flag, add a changelog entry for the final
feature implementation, and refactor the associated specs

app/serializers/merge_request_widget_entity.rb

@@ -151,6 +151,10 @@ class MergeRequestWidgetEntity < Grape::Entity
       can?(current_user, :create_pipeline, merge_request.source_project)
   end
 
+  def use_merge_base_with_merged_results?
+    object.actual_head_pipeline&.merge_request_event_type == :merged_result
+  end
+
   def head_pipeline_downloadable_path_for_report_type(file_type)
     object.head_pipeline&.present(current_user: current_user)
       &.downloadable_path_for_report_type(file_type)
@@ -161,11 +165,6 @@ class MergeRequestWidgetEntity < Grape::Entity
       &.downloadable_path_for_report_type(file_type)
   end
 
-  def use_merge_base_with_merged_results?
-    Feature.enabled?(:merge_base_pipelines, object.target_project) &&
-      object.actual_head_pipeline&.merge_request_event_type == :merged_result
-  end
-
   def merge_base_pipeline_downloadable_path_for_report_type(file_type)
     object.merge_base_pipeline&.present(current_user: current_user)
       &.downloadable_path_for_report_type(file_type)

changelogs/unreleased/remove-merge-base-pipelines-feature-flag.yml

+---
+title: Use updated base report for CodeQuality MergeRequest widdget
+merge_request: 46384
+author:
+type: changed

config/feature_flags/development/merge_base_pipelines.yml

----
-name: merge_base_pipelines
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/44648
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/263724
-type: development
-group: group::testing
-default_enabled: false

spec/serializers/merge_request_widget_entity_spec.rb

@@ -106,29 +106,16 @@ RSpec.describe MergeRequestWidgetEntity do
       let(:merge_base_job_id) { merge_base_pipeline.builds.first.id }
 
       it 'has head_path and base_path entries' do
-        expect(subject[:codeclimate][:head_path]).to be_present
-        expect(subject[:codeclimate][:base_path]).to be_present
+        expect(subject[:codeclimate][:head_path]).to include("/jobs/#{generic_job_id}/artifacts/download?file_type=codequality")
+        expect(subject[:codeclimate][:base_path]).to include("/jobs/#{generic_job_id}/artifacts/download?file_type=codequality")
       end
 
       context 'on pipelines for merged results' do
         let(:pipeline) { create(:ci_pipeline, :merged_result_pipeline, :with_codequality_report, project: project) }
 
-        context 'with merge_base_pipelines enabled' do
-          it 'returns URLs from the head_pipeline and merge_base_pipeline' do
-            expect(subject[:codeclimate][:head_path]).to include("/jobs/#{generic_job_id}/artifacts/download?file_type=codequality")
-            expect(subject[:codeclimate][:base_path]).to include("/jobs/#{merge_base_job_id}/artifacts/download?file_type=codequality")
-          end
-        end
-
-        context 'with merge_base_pipelines disabled' do
-          before do
-            stub_feature_flags(merge_base_pipelines: false)
-          end
-
-          it 'returns URLs from the head_pipeline and base_pipeline' do
-            expect(subject[:codeclimate][:head_path]).to include("/jobs/#{generic_job_id}/artifacts/download?file_type=codequality")
-            expect(subject[:codeclimate][:base_path]).to include("/jobs/#{generic_job_id}/artifacts/download?file_type=codequality")
-          end
+        it 'returns URLs from the head_pipeline and merge_base_pipeline' do
+          expect(subject[:codeclimate][:head_path]).to include("/jobs/#{generic_job_id}/artifacts/download?file_type=codequality")
+          expect(subject[:codeclimate][:base_path]).to include("/jobs/#{merge_base_job_id}/artifacts/download?file_type=codequality")
         end
       end
     end