Kill off CI jobs

After a PR is filed, it would be awesome to be able to cancel all/individual CI builds and mark them as failures/successes. To save time and resources. Not too seldom, when a PR has been filed the author realizes something that is wrong or bad in the commit and then it is useless to let a hundred jobs continue for a long time. It would be very useful and save money, energy and resources if we then could just cancel them easily.

Many of us have limited CI parallelims, so having CI jobs run “in vain” can seriously delay the other “real” jobs to get started and performed.