chore(ci variables): update the ci_variables.json

This merge request is the result of running the script to update the CI/CD variable definition. There is no manual editing in this commit. The content of ci_variables.json is scraped from the official GitLab documentation.

Documentation: https://gitlab.com/gitlab-org/gitlab-vscode-extension/-/blob/main/docs/developer/ci-variables.md

A script generated this code change, so this merge request will merge without a second review.