Run CI danger job even if user canceled it while it was running

Limitation: The after_script is not executed if the job did not start at
all, i.e. if the user canceled the job before it got onto a runner.
See https://gitlab.com/groups/gitlab-org/-/epics/10158

(cherry picked from commit 33bc2628b7)

.gitlab-ci.yml

@@ -660,6 +660,10 @@ danger:
   script:
     - pip install git+https://gitlab.isc.org/isc-projects/hazard.git
     - hazard
+  after_script:
+    # insist on running danger job even if user canceled it while it was running
+    - test "$CI_JOB_STATUS" != "canceled" && exit 0
+    - !reference [danger, script]
   rules:
     - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'