gitlab-ci: Use stable build path on Windows
While at it, use a shorter work directory everywhere.
With https://gitlab.com/gitlab-org/gitlab-runner/-/merge_requests/2122 deployed on our Windows runners, we can do this now.
While at it, use a shorter work directory everywhere.
With https://gitlab.com/gitlab-org/gitlab-runner/-/merge_requests/2122 deployed on our Windows runners, we can do this now.