icaldir: fix build after configuration porting

Commit 4b71d5ea introduced a porting change of the configuration
for the icaldir resource. The settingsdialog.ui file was renamed, but
the reference from the CMake script remained causing a build failure.

Fix this by removing the line as it is now obsolete.

Revievers: mlaurent, dvratil

Reviewerd By: mlaurent, dvratil

Differential Revision: https://phabricator.kde.org/D19196