Fixed the problem that copying the default theme at halo startup did not use themeId as the theme folder name

Created by: guqing

What this PR does?

修复 Halo 启动时拷贝默认主题没有使用themeId作为主题文件夹名称的问题 See #1548 合并时需要 cherry-pick 到 release-1.4

Why we need it?

启动时拷贝默认主题应使用themeId以避免主题在线更新后文件夹名称不一致导致部分文件无法获取

How to test it?

删除halo work dir下的默认主题anatole,然后启动halo查看默认主题文件夹名称是否为caicai_anatole 点击在线更新或上传该主题的更新包查看主题文件夹名称是否一致，同为caicai_anatole