Sync bot crushing partial reviews

Hi @iliakan

I discovered this in the Spanish repo,
but happens in the other repos too.
...

Previously, the bot used different branches for sync, closing the old PR and generating a new one over a new branch. Partial reviews were preserved in the closed PR.

Now, the bot closes the old PR but always uses the same branch, doing a force push on it that destroys any partial reviews.

未指定檔案、測試或進入點。先定位 sync bot 對分支和 pull request 的處理，然後重現一次包含部分 review 的同步；當同步不再透過 force-push 覆蓋已 review 的工作並保留 review 上下文時，即視為完成。