ci: Build the CI trigger container as part of valve-infra
See mesa/mesa!14660 (merged) (comment 1228758) for the original suggestion. A userland will be needed from various projects in Gitlab CI to submit b2c jobs to the executor. It's a little questionable whether this container should live in the boot2container namespace or the valve-infra namespace, since the requirements this container honours are split b
This was moved from mupuf/boot2container!27 (closed)