ci(docs): fix merged update runtime drift

[wuhuizuo]

Summary

• switch docs/docs-cn merged-update postsubmits to the published ghcr.io/pingcap-qe/ci/docs-pdf-runtime manifest digest
• remove the stale docs/docs-cn Jenkins DSL wrappers that still pointed at deleted pipeline files

Changes

• update prow-jobs/pingcap/docs/latest-postsubmits.yaml
• update prow-jobs/pingcap/docs-cn/latest-postsubmits.yaml
• delete jobs/pingcap/docs/latest/merged_update_docs.groovy
• delete jobs/pingcap/docs-cn/latest/merged_update_docs_cn.groovy

Testing

• ruby -e 'require "yaml"; %w[prow-jobs/pingcap/docs/latest-postsubmits.yaml prow-jobs/pingcap/docs-cn/latest-postsubmits.yaml].each { |f| YAML.load_file(f); puts "OK #{f}" }'
• rg -n "merged_update_docs(_cn)?\\.groovy|pingcap/docs/merged_update_docs|pingcap/docs-cn/merged_update_docs_cn|docs-merged-update-runtime" -S .

Risk

• low; only the two docs postsubmit image refs and the dead Jenkins wrappers are touched
• rollback is a revert of this PR if the new GHCR runtime digest needs to change

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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Details

Needs approval from an approver in each of these files:

• jobs/OWNERS
• prow-jobs/pingcap/docs/OWNERS
• prow-jobs/pingcap/docs-cn/OWNERS

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[ti-chi-bot]

I have already done a preliminary review for you, and I hope to help you do a better job.

Summary:
This PR updates the image references in the docs and docs-cn prow postsubmit job YAML files to point to a newly published container image on GHCR, replacing the previous image hosted on Google Artifact Registry. It also removes stale Jenkins DSL pipeline job definitions that referenced deleted pipeline scripts, cleaning up legacy configuration. The changes are straightforward, low-risk, and well scoped. The YAML and Groovy files are consistent with the PR description, and basic YAML loading and grep tests were performed.

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Code Improvements:

• prow-jobs/pingcap/docs/latest-postsubmits.yaml and prow-jobs/pingcap/docs-cn/latest-postsubmits.yaml (lines ~17):
  • The new image digest is hardcoded; consider adding a comment or referencing a centralized version/digest source if this digest needs to be updated often. This reduces risk of drift or errors during manual updates.
  • Example suggestion:

    # Image digest updated to latest published version as of YYYY-MM-DD
    image: ghcr.io/pingcap-qe/ci/docs-pdf-runtime@sha256:0d5be9adbbce839dc151827a08d6e8d85ce1a98a62e02958f3a314f8420ab064

  This improves maintainability.

Best Practices:

• Testing Description:

  • The testing command uses ruby to load YAML files for syntax validation, which is good. Consider adding explicit validation that the new image references are used in the prow job definitions by adding a test or script to verify the prow job registration if possible.
  • The grep commands are helpful for confirming no references to removed groovy files remain.

• Documentation:

  • The PR description is clear but consider adding a brief note on how the new image was built or where to find its manifest for future reference. This will assist maintainers tracking image updates.

• Deleted Groovy Files (jobs/pingcap/docs/latest/merged_update_docs.groovy and docs-cn counterpart):

  • Since these files define Jenkins jobs, verify that no active Jenkins pipelines depend on them beyond this repo to avoid disruption. This may be outside this repo but worth double-checking.

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No critical issues identified.
The PR is focused, low risk, and improves CI configuration hygiene and runtime consistency. Suggestions are mainly around maintainability and documentation.