Change `jq` query in CI scripts to Python code

[agoscinski]

In PR #6573 the readability of the jq query was criticized, but since the PR only fixes something with the query, I did not want to spent the time immediately to change it to Python.

I am honestly quite unhappy about this obscure jq syntax. Perhaps we should switch to javascript to make this more readable. This was recommended to me here:

https://github.com/docker/bake-action/issues/239#issuecomment-2285948802

Originally posted by @danielhollas in https://github.com/aiidateam/aiida-core/pull/6573#discussion_r1778321788