Hotfix/ci make jobs interruptible

[rmelotte]

Essentially 2 things:

• Make the CI jobs interruptible. This should hopefully make it overall faster, because redundant pipelines will get cancelled (a pipeline is redundant when there is a more recent one for the same branch). Only the latest pipeline for each branch will get completed.
• Cleanup the certification tests manually, this should hopefully improving the situation when a job is cancelled (the next ones should no longer fail).