[ci] cancel pipeline if test-linux-stable fail (#5066)

* [Do not merge] cancel pipeline if test-linux-stable fail

* empty commit for pipeline rerun

* fix test-linux-stable

* fail test-linux-stable

* empty commit for pipeline rerun

* fix test-linux-stable

* Update .gitlab-ci.yml

Co-authored-by: Denis Pisarev <denis.pisarev@parity.io>

* small fixes

* add needs

Co-authored-by: Denis Pisarev <denis.pisarev@parity.io>

polkadot/.gitlab-ci.yml

@@ -803,3 +803,25 @@ publish-rustdoc:
     - echo "___Rustdoc was successfully published to https://paritytech.github.io/polkadot/___"
   after_script:
     - rm -rf .git/ ./*
+
+#### stage:                        .post
+
+# This job cancels the whole pipeline if any of provided jobs fail.
+# In a DAG, every jobs chain is executed independently of others. The `fail_fast` principle suggests
+# to fail the pipeline as soon as possible to shorten the feedback loop.
+cancel-pipeline:
+  stage:                           .post
+  needs:
+    - job:                         test-linux-stable
+      artifacts:                   false
+    - job:                         check-runtime-benchmarks
+      artifacts:                   false
+    - job:                         check-try-runtime
+      artifacts:                   false
+  rules:
+    - if: $CI_COMMIT_REF_NAME =~ /^[0-9]+$/                         # PRs
+      when: on_failure
+  variables:
+    PROJECT_ID:                    "${CI_PROJECT_ID}"
+    PIPELINE_ID:                   "${CI_PIPELINE_ID}"
+  trigger:                         "parity/infrastructure/ci_cd/pipeline-stopper"