[Uri Filter Search Provider] readName() of KDesktopFile

In 6246cc48 this code was ported away from KServiceTypeTrader where accidentally a service->name()
which returns the translated name of the service to KDesktopFile::name() which returns the
file path of the desktop file.

CHANGELOG: Fixed webshortcuts showing their file path instead of their human-readable name

Differential Revision: https://phabricator.kde.org/D9405