Improve gitlab-ci for speed and size
.gitlab-ci.yml: Remove artifacts after two weeks to conserve space. Make all jobs interruptable, to not run jobs that would be superseded by newer ones (in follow-up commits or when force-pushing).
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.gitlab-ci.yml: Remove artifacts after two weeks to conserve space. Make all jobs interruptable, to not run jobs that would be superseded by newer ones (in follow-up commits or when force-pushing).