add maximum lifetime of connections (#21368) (#21369)#21370

ti-chi-bot[bot] merged 2 commits intopingcap:release-8.5pingcap/docs-cn:release-8.5from

ti-chi-bot:cherry-pick-21369-to-release-8.5ti-chi-bot/docs-cn:cherry-pick-21369-to-release-8.5Copy head branch name to clipboard