Deleting arbitrary imaging sequence in the Capture module corrected.

Summary:
Currently, when marking a single row and pressing the delete button, always the first row gets deleted and not the selected one.

As a fix, I created a new public slot removeJobFromQueue(), since removeJob(int) is always invoked with index=0 when the delete button is pushed. Maybe there is a more elegant way, but it seems like the slot obtains an (empty) argument when invoked through the push button event instead of none, which would lead to index=-1 as defined in the header file.

Test Plan: Open the Capture module and create multiple imaging rows. Try to delete any of them and check, whether the correct one disappears.

Reviewers: mutlaqja, TallFurryMan

Reviewed By: mutlaqja, TallFurryMan

Subscribers: kde-edu

Tags: KDE Edu

Differential Revision: https://phabricator.kde.org/D19426