Improve checks on folding/branching

Background

As explained in apertis-infrastructure!216 (comment 150760) the folding and branching pipelines should help to identify potential issues, like packages which have not reached the APT repos, to avoid releasing unhealty images.

Outcomes

TBD

Management data

This section is for management only, it should be the last one in the description.

/cc @em @Balasubramanian @sudarshan @wlozano

Phabricator link: https://phabricator.apertis.org/T10872