tiflash: Clarified profiles.default.max_memory_usage_for_all_queries and fix typo (#20503)#20513

ti-chi-bot[bot] merged 4 commits intopingcap:release-8.5pingcap/docs-cn:release-8.5from

ti-chi-bot:cherry-pick-20503-to-release-8.5ti-chi-bot/docs-cn:cherry-pick-20503-to-release-8.5Copy head branch name to clipboard