chore(cicd): use image for extract-script job

.gitlab-ci.yml

 include:
+  - project: 'to-be-continuous/tools/gitlab-ci'
+    ref: 'master'
+    file: '/templates/extract.yml'
   - project: 'to-be-continuous/tools/gitlab-ci'
     ref: 'master'
     file: '/templates/validation.yml'
@@ -20,21 +23,6 @@ variables:
   GITLAB_CI_FILES: "templates/gitlab-ci-gcloud.yml"
   BASH_SHELLCHECK_FILES: "*.sh"
 
-# extract the Bash script from template (for ShellCheck job)
-extract-script:
-  stage: .pre
-  script:
-    - echo "#!/bin/bash" > script.sh
-    - sed -n '/BEGSCRIPT/,/ENDSCRIPT/p' "$GITLAB_CI_FILES" | sed 's/^  //' >> script.sh
-    - export LC_ALL=C.UTF-8
-  artifacts:
-    when: always
-    name: extracted template script
-    expire_in: 1h
-    paths:
-      - script.sh
-
-
 semantic-release:
   rules:
     # on production branch(es): auto if SEMREL_AUTO_RELEASE_ENABLED