v8.5.5: Add index lookup push down content (#22196)#22252

ti-chi-bot[bot] merged 2 commits intopingcap:feature/preview-v8.5.5pingcap/docs:feature/preview-v8.5.5from

ti-chi-bot:cherry-pick-22196-to-release-8.5ti-chi-bot/docs:cherry-pick-22196-to-release-8.5Copy head branch name to clipboard