Handling of aborts during parking/unparking of rolloff roofs corrected

Summary: Aborting parking and unparking for rolloff roofs led to states where the respective action could not be continued, sinse the buttons were not enabled correctly. This patch fixes this so that parking, unparking, closing and opening of rolloff roofs can be aborted and continued afterwards.

Test Plan: Unpark, park, open or close the roof and abort the respective action. Check, whether it can be continued as expected.

Reviewers: mutlaqja

Reviewed By: mutlaqja

Subscribers: yurchor, kde-edu

Tags: KDE Edu

Differential Revision: https://phabricator.kde.org/D24064