ci(pipelines): remove Debug info stage (#4330)## What changed- Remove the `Debug info` stage from Jenkins pipelines under`pipelines/`.## Why- This stage mostly printed environment/network diagnostics and wasredundant/noisy across pipelines.## Testing- Static Jenkinsfile validation:- `JENKINS_URL=https://do.pingcap.net/jenkins.ci/verify-jenkins-pipelines.sh`## Notes- Replay testing can be triggered in the PR if needed (e.g. `/testpull-replay-jenkins-pipelines`). (commit: 690e20e)