[DeleteJob] Use a separate worker thread to run actual IO operation
Summary:
BUG: 390748
FIXED-IN: 5.65
Reviewers: dfaure, Frameworks
Reviewed By: dfaure
Subscribers: kde-frameworks-devel
Tags: Frameworks
Maniphest Tasks: T11627
Differential Revision: https://phabricator.kde.org/D24962