Revert "Add default shortcut to switch to the desktop to the left/right/top/bottom"

I nack this change. This needs to be discussed more and a different solution
needs to be found. See constraints defined in:
https://phabricator.kde.org/D24281#578243

This reverts commit 20ca3bb57a5f9cb2d589490fb2cb51af20ed84fe.