Change: Remove set as description space action

BREAKING CHANGE: In order to eliminate complexity and reduce confusion, we removed the "Set as description" space action.
This action was not used frequently and was not necessary for the user experience.
The space description can still be simply updated via the "Edit description" action.

https://github.com/owncloud/web/pull/11277
https://github.com/owncloud/web/issues/11276
