ddl: use the correct timezone to encode record for adding index (#46055)#46103

ti-chi-bot[bot] merged 3 commits intopingcap:release-7.1pingcap/tidb:release-7.1from

ti-chi-bot:cherry-pick-46055-to-release-7.1ti-chi-bot/tidb:cherry-pick-46055-to-release-7.1Copy head branch name to clipboard