CI: remove stale workflow [skip ci]

[pascalgrimaud]

Following the discussion at https://groups.google.com/g/jhipster-dev/c/M1IKwib7i08/m/nQd8yNLxBQAJ

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Please make sure the below checklist is followed for Pull Requests.

• All continuous integration tests are green
• Tests are added where necessary
• The JDL part is updated if necessary
• jhipster-online is updated if necessary
• Documentation is added/updated where necessary
• Coding Rules & Commit Guidelines as per our CONTRIBUTING.md document are followed

When you are still working on the PR, consider converting it to Draft (below reviewers) and adding skip-ci label, you can still see CI build result at your branch.