/etc/xdg/pimcommon.categories is in libkf5pimcommon-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.pimcommon kdepim (pimcommon)
org.kde.pim.pimcommonakonadi kdepim (pimcommonakonadi)
|