/etc/xdg/libkleo.categories is in libkf5libkleo-data 4:17.12.3-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | org.kde.pim.kleo_ui libkleo (kleo_ui)
org.kde.pim.gpgme_backend libkleo (gpgme_backend)
|