tiflash: Remove the description about expr_blacklist in use_tiflash.md (#6188)#6276

ti-chi-bot merged 4 commits into

pingcap:release-4.0pingcap/docs:release-4.0from

ti-chi-bot:cherry-pick-6188-to-release-4.0ti-chi-bot/docs:cherry-pick-6188-to-release-4.0Copy head branch name to clipboard