Merging `master` into other branches is hard

[hofstee]

Whenever scripts and CI definitions update on master, the changes need to be propagated to the other branches for the Buildkite CI to work. Additionally, we usually want to have the branches running the most updated version of CI they can.

One way to fix this might be to create a scripts branch where updating the scripts is done and then merging that into both master and the other branches.