Move the pipeline statistics reporting out of the extract-source job

IMO, the code introduced by !622 (merged) at https://salsa.debian.org/salsa-ci-team/pipeline/-/blob/b27b7da64eee01138204cd979dc3dd55a804a400/salsa-ci.yml#L204-216 shouldn't be placed inside the extract-source job.

Thinking about !569, I don't see this as part of any of the build jobs, which will be on the first stage run for the pipeline. IMO, the code of this opt-in feature should be found in a separate job, on a specific stage (that could run in parallel of the build stage). @44yu5h, could you please move the related before_script out of the extract-source job please?