Add quotes to prevent potential word splittings

[zzmic]

As the title suggests, this PR includes the commit that adds quotes to several commands in build/linux/online_install.sh and build/linux/uninstall.sh to prevent potential word splittings (related to https://www.shellcheck.net/wiki/SC2086). For instance, rm -rf $tar_path is risky because tar_path is derived from base_path, which in turn comes from user input via zenity. If the user enters a path containing spaces, the unquoted variable could be split into multiple arguments, causing the command to behave unexpectedly.

如下为翻译：正如标题所示，本次PR包含在build/linux/online_install.sh和build/linux/uninstall.sh中为多个命令添加引号的提交，以防止潜在的单词分割问题（与https://www.shellcheck.net/wiki/SC2086相关）。例如，rm -rf $tar_path 存在风险，因为 tar_path 由 base_path 派生而来，而后者又来自用户通过 zenity 输入的路径。若用户输入的路径包含空格，未加引号的变量可能被拆分为多个参数，导致命令行为异常。