/etc/xdg/libkgapi.categories is in libkpimgapi-data 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.kgapi libkgapi (General debug)
org.kde.kgapi.raw libkgapi (Raw debug)
|