error message for `unstake` is not user friendly

Currently during stake pool unlock, we show this error

it should be more like:

sp-unlock not allowed until all active allocations are cancelled by respective owners. So that users know the reason for the error.

在 CLI 代码库中查找在质押池解锁期间显示的错误消息，很可能在命令处理文件如 `cmd/unstake.go` 或类似文件中。找到当前通用错误生成的位置，并将其更新为提供的更具描述性的文本。通过在具有活跃分配的场景中运行 unstake 命令来测试更改，以验证新消息是否出现。

由索引模型根据 Issue 内容生成。