/usr/share/desktop-directories/ is in plasma-workspace 4:5.5.5.2-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/desktop-directories/kf5-development-translation.directory
/usr/share/desktop-directories/kf5-development-webdevelopment.directory
/usr/share/desktop-directories/kf5-development.directory
/usr/share/desktop-directories/kf5-editors.directory
/usr/share/desktop-directories/kf5-edu-languages.directory
/usr/share/desktop-directories/kf5-edu-mathematics.directory
/usr/share/desktop-directories/kf5-edu-miscellaneous.directory
/usr/share/desktop-directories/kf5-edu-science.directory
/usr/share/desktop-directories/kf5-edu-tools.directory
/usr/share/desktop-directories/kf5-education.directory
/usr/share/desktop-directories/kf5-games-arcade.directory
/usr/share/desktop-directories/kf5-games-board.directory
/usr/share/desktop-directories/kf5-games-card.directory
/usr/share/desktop-directories/kf5-games-kids.directory
/usr/share/desktop-directories/kf5-games-logic.directory
/usr/share/desktop-directories/kf5-games-roguelikes.directory
/usr/share/desktop-directories/kf5-games-strategy.directory
/usr/share/desktop-directories/kf5-games.directory
/usr/share/desktop-directories/kf5-graphics.directory
/usr/share/desktop-directories/kf5-internet-terminal.directory
/usr/share/desktop-directories/kf5-internet.directory
/usr/share/desktop-directories/kf5-main.directory
/usr/share/desktop-directories/kf5-more.directory
/usr/share/desktop-directories/kf5-multimedia.directory
/usr/share/desktop-directories/kf5-office.directory
/usr/share/desktop-directories/kf5-science.directory
/usr/share/desktop-directories/kf5-settingsmenu.directory
/usr/share/desktop-directories/kf5-system-terminal.directory
/usr/share/desktop-directories/kf5-system.directory
/usr/share/desktop-directories/kf5-toys.directory
/usr/share/desktop-directories/kf5-unknown.directory
/usr/share/desktop-directories/kf5-utilities-accessibility.directory
/usr/share/desktop-directories/kf5-utilities-desktop.directory
/usr/share/desktop-directories/kf5-utilities-file.directory
/usr/share/desktop-directories/kf5-utilities-peripherals.directory
/usr/share/desktop-directories/kf5-utilities-pim.directory
/usr/share/desktop-directories/kf5-utilities-xutils.directory
/usr/share/desktop-directories/kf5-utilities.directory