Summary:
This option don't work as expected for years on X, and current wayland protocol don't allow to have a proper size for all application (each framework came with this own solution for this option, that mean we will not have same cursor size on different application)

We set default size as 24

BUG: 385920
BUG: 413783

Reviewers: #plasma, meven, davidedmundson, ngraham

Reviewed By: ngraham

Subscribers: ngraham, plasma-devel, kde-doc-english

Tags: #plasma, #documentation

Maniphest Tasks: T12040

Differential Revision: https://phabricator.kde.org/D28652