Move `before_script` scripts into `script`

It doesn't really make sense to utilize before_script here, since its primary function is to overwrite global before_script set in the pipeline. This made it impossible for a job to define its own steps to execute before script without copying the whole before_script section from this file, which makes it easily out of date (and is something that already happened for package:deb-pureos-amber job in phosh as it doesn't use eatmydata like other jobs do now).