ci: merge the cheap script gates into one job; cancel superseded bench runs - #6204

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: ASzc/change-string-case-action@v5, docker/build-push-action@v4, docker/login-action@v2. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/