dir: Only reuse system cache dirs with permissions 0755
dir: Only reuse system cache dirs with permissions 0755

We need this to ensure that the dir can be shared with the new
system-helper flatpak user. Old dirs can happen to get less
permissions if there was a umask set when it was created.

Closes: #2856
Approved by: alexlarsson

matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak