Add auto-cancel for pending pipelines on branch, if they are not HEAD

What does this MR do?

Decrease entropy in Gitlab universe

First iteration for #8998 (closed)

• Adds option "Auto-cancel pending pipelines" in "CI/CD Pipelines" project settings tab: when checkbox checked, all pending non-HEAD pipelines will be canceled by system, automatizing scenario:

  1. "User creates pipeline for branch" / "User pushes commit to gitlab"
  2. User goes to pipelines index page and cancel unnecessary (only pending) pipelines.

• Adds target: '_blank' to doc links in "CI/CD Pipelines" project settings tab

• Refactor spec/services/ci/create_pipeline_service_spec.rb, extracting execute_service method

UI:

• Pipeline list:
  • Tooltip on canceled status badge
• MR widget/commit widget:
  • Pipeline #12345678 was auto-canceled.. etc
  • Hovering over the words auto-canceled will bring the same tooltips
• Pipeline page:
  • Tooltip on canceled status badge
• Pipeline graph job node:
  • has improved tooltip with auto-canceled (not anything else)
• Mini pipeline graph stage and job status icons
  • has improved tooltip with auto-canceled (not anything else)
• Job list
  • Tooltip on canceled status badge
• Job list in pipeline view
  • Tooltip on canceled status badge
• Job view
  • Tooltip on canceled status badge

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Many reasons are discussed here #8998 (closed)

Screenshots (if relevant)

Option in CI/CD Pipelines Project settings tab:

Pipeline list:

Pipeline page:

Job list:

Job view:

Job list in pipeline view:

Setting:

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

#8998 (closed)

spec/services/ci/create_pipeline_service_spec.rb

@@ -21,6 +21,12 @@ def execute_service(after: project.commit.id, message: 'Message', ref: 'refs/hea
     context 'valid params' do
       let(:pipeline) { execute_service }
 
+      let(:pipeline_on_previous_commit) do
+        execute_service(
+          after: previous_commit_sha_from_ref('master')
+        )
+      end
+
       it { expect(pipeline).to be_kind_of(Ci::Pipeline) }
       it { expect(pipeline).to be_valid }
       it { expect(pipeline).to eq(project.pipelines.last) }
@@ -29,20 +35,10 @@ def execute_service(after: project.commit.id, message: 'Message', ref: 'refs/hea
       it { expect(pipeline.builds.first).to be_kind_of(Ci::Build) }
 
       context 'auto-cancel enabled' do
-        let(:pipeline_on_previous_commit) do
-          execute_service(
-            after: previous_commit_sha_from_ref('master')
-          )
-        end
-
         before do
           project.update(auto_cancel_pending_pipelines: 'enabled')
         end
 
-        def previous_commit_sha_from_ref(ref)
-          project.commit(ref).parent.sha
-        end
-
         it 'does not cancel HEAD pipeline' do
           pipeline
           pipeline_on_previous_commit
@@ -81,6 +77,24 @@ def previous_commit_sha_from_ref(ref)
           expect(pending_pipeline.reload).to have_attributes(status: 'pending', auto_canceled_by_id: nil)
         end
       end
+
+      context 'auto-cancel disabled' do
+        before do
+          project.update(auto_cancel_pending_pipelines: 'disabled')
+        end
+
+        it 'does not auto cancel pending non-HEAD pipelines' do
+          pipeline_on_previous_commit
+          pipeline
+
+          expect(pipeline_on_previous_commit.reload)
+            .to have_attributes(status: 'pending', auto_canceled_by_id: nil)
+        end
+      end
+
+      def previous_commit_sha_from_ref(ref)
+        project.commit(ref).parent.sha
+      end
     end
 
     context "skip tag if there is no build for it" do