xdg-mime: actually handle lists in mimeapps.list correctly

The issue was raised in [1]. The earlier fix [2] makes xdg-mime always
pick the first item from a list, and that differs from the standard [3].

> If the application is no longer installed, the next application in the
> list is attempted, and so on.

A latter fix [4] implements the standard-compliant behavior, while it
does not actually work until [2] is reverted.

[1] https://bugs.freedesktop.org/show_bug.cgi?id=44163
[2] https://gitlab.freedesktop.org/xdg/xdg-utils/-/commit/a5ec775d
[3] https://specifications.freedesktop.org/mime-apps-spec/1.0.1/ar01s04.html
[4] https://gitlab.freedesktop.org/xdg/xdg-utils/-/commit/1f8e58d5