fix(operator): 删除依赖 rcon-cli 的 preStop 死代码，缩容前由 operator 经 RCON 执行 save-all flush

docs/troubleshooting.md

@@ -256,7 +256,7 @@ What holds the world, in order:
    ```
 
 A restore, backup or file write refused with `409 not_stopped` although the
-panel shows `Stopped` means the game pod is still terminating (its preStop save
+panel shows `Stopped` means the game pod is still terminating (its shutdown save
 can take a while); retry once `kubectl -n minecraft get pods -l
 felis.lolicon.best/server=<name>` shows nothing.