fix: [ulnfs] Prioritize the mounting method for long file names

[pppanghu77]

Do not mount dlnfs while enabling ulnfs

Log: [ulnfs] Prioritize the mounting method for long file names
Task: https://pms.uniontech.com/task-view-359649.html

[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: pppanghu77

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[deepin-ci-robot]

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关键摘要:

• 在新增的代码中，变量 ulnfs_enable 的赋值方式可能会导致歧义，建议使用 = 而不是 == 来赋值。
• 条件判断中使用了两个连续的 && 操作符，这可能会导致逻辑错误，建议使用 -a 或者 -o 操作符来组合多个条件。
• 新增的代码中没有处理 ulnfs_enable 为 true 的情况，如果需要同时检查 dlnfs_enable 和 ulnfs_enable，应该添加相应的逻辑。

是否建议立即修改:

• 是