When building the file attribute table info for local files, use
thumbnail paths in $XDG_CACHE_DIR/thumbnails/large in addition to
$XDG_CACHE_DIR/thumbnails/normal.

Failing to do this would cause an application that creates large
thumbnails by default to never find any value for
G_FILE_ATTRIBUTE_THUMBNAIL_PATH, with no
G_FILE_ATTRIBUTE_THUMBNAILING_FAILED set, which might cause the
application to either think thumbnailing is still in progress, or
blindly requeue thumbnail operations in a loop.

Large thumbnails are generally preferred, so we now default to the path
of a large thumbnail (in case both are present).

https://bugzilla.gnome.org/show_bug.cgi?id=686895