Removed pipeline_ci_sources_only feature flag

Removing the pipeline_ci_sources_only feature flag introduced
in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/23353

app/models/project.rb

@@ -256,7 +256,7 @@ class Project < ActiveRecord::Base
   # other pipelines, like webide ones, that we won't retrieve
   # if we use this relation.
   has_many :ci_pipelines,
-          -> { Feature.enabled?(:pipeline_ci_sources_only, default_enabled: true) ? ci_sources : all },
+          -> { ci_sources },
           class_name: 'Ci::Pipeline',
           inverse_of: :project
   has_many :stages, class_name: 'Ci::Stage', inverse_of: :project

spec/models/project_spec.rb

@@ -145,25 +145,10 @@ describe Project do
     end
 
     describe 'ci_pipelines association' do
-      context 'when feature flag pipeline_ci_sources_only is enabled' do
-        it 'returns only pipelines from ci_sources' do
-          stub_feature_flags(pipeline_ci_sources_only: true)
+      it 'returns only pipelines from ci_sources' do
+        expect(Ci::Pipeline).to receive(:ci_sources).and_call_original
 
-          expect(Ci::Pipeline).to receive(:ci_sources).and_call_original
-
-          subject.ci_pipelines
-        end
-      end
-
-      context 'when feature flag pipeline_ci_sources_only is disabled' do
-        it 'returns all pipelines' do
-          stub_feature_flags(pipeline_ci_sources_only: false)
-
-          expect(Ci::Pipeline).not_to receive(:ci_sources).and_call_original
-          expect(Ci::Pipeline).to receive(:all).and_call_original.at_least(:once)
-
-          subject.ci_pipelines
-        end
+        subject.ci_pipelines
       end
     end
   end