fix: the dual screen expandsion position when scaled

[add-uos]

fix the dual screen expandsion position when scaled

Log: fix the dual screen expandsion position when scaled Bug: https://pms.uniontech.com/bug-view-273083.html

[deepin-ci-robot]

deepin pr auto review

关键摘要:

• 在获取环境变量时，应该检查环境变量是否存在，而不是直接使用 qgetenv。
• 使用 QDBusInterface 获取缩放因子时，应该处理可能的异常情况，例如 QDBusReply 的失败。
• qDebug 应该在调试模式下使用，不应该在生产代码中留下调试信息。
• 缩放因子的处理逻辑应该更加健壮，例如检查 QDBusReply 是否成功。

是否建议立即修改:

• 是

[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: add-uos, lzwind

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Needs approval from an approver in each of these files: - **[debian/deepin/OWNERS](https://github.com/linuxdeepin/deepin-screen-recorder/blob/release/eagle/debian/deepin/OWNERS)** Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[add-uos]

/merge