Use QTemporaryDir::filePath() instead of path concatenation
Summary:
This is the preferred way to get a file path in a temporary
directory. It's easy to forget to append '/' when using
QTemporaryDir::path().
Reviewers: Plasma, hein
Reviewed By: Plasma, hein
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D10038