D15417: [AppImage Thumbnailer] Avoid creating QTemporaryFile

[TheAssassin]

TheAssassin accepted this revision.
This revision is now accepted and ready to land.

REPOSITORY
  R320 KIO Extras

REVISION DETAIL
  https://phabricator.kde.org/D15417

To: broulik, #frameworks, TheAssassin, anthonyfieroni