[ci] small fix for job switcher (#1990)

Author: alvicsam

.gitlab-ci.yml

@@ -44,6 +44,7 @@ variables:
 # they will be used if the job fails
 .pipeline-stopper-vars:
   before_script:
+    - !reference [.job-switcher, before_script]
     - echo "FAILED_JOB_URL=${CI_JOB_URL}" > pipeline-stopper.env
     - echo "FAILED_JOB_NAME=${CI_JOB_NAME}" >> pipeline-stopper.env
     - echo "FAILED_JOB_NAME=${CI_JOB_NAME}" >> pipeline-stopper.env
@@ -181,4 +182,3 @@ remove-cancel-pipeline-message:
     PR_NUM:                        "${CI_COMMIT_REF_NAME}"
   trigger:
     project:                       "parity/infrastructure/ci_cd/pipeline-stopper"
-    branch:                        "as-improve"