Disable interruptible pipeline feature flag by default

app/services/ci/create_pipeline_service.rb

@@ -95,7 +95,7 @@ module Ci
     # rubocop: disable CodeReuse/ActiveRecord
     def auto_cancelable_pipelines
       # TODO: Introduced by https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/23464
-      if Feature.enabled?(:ci_support_interruptible_pipelines, project, default_enabled: true)
+      if Feature.enabled?(:ci_support_interruptible_pipelines, project, default_enabled: false)
         project.ci_pipelines
           .where(ref: pipeline.ref)
           .where.not(id: pipeline.id)

spec/services/ci/create_pipeline_service_spec.rb

@@ -317,9 +317,14 @@ describe Ci::CreatePipelineService do
 
         context 'interruptible builds' do
           before do
+            Feature.enable(:ci_support_interruptible_pipelines)
             stub_ci_pipeline_yaml_file(YAML.dump(config))
           end
 
+          after do
+            Feature.disable(:ci_support_interruptible_pipelines)
+          end
+
           let(:config) do
             {
               stages: %w[stage1 stage2 stage3 stage4],