Investigate: Regressions in 8.4 plugin docs

[karenzone]

Investigate regressions introduced in https://github.com/elastic/logstash-docs/pull/1434

Findings

It appears that the PR was generated using the old job rather than the new Github action.

Testing/Remediation

• I closed https://github.com/elastic/logstash-docs/pull/1434, and re-ran the job using the Github action. It resulted in #1436 with no regressions.
• I updated all three Logstash release checklists to point to the github action.