[CI] Make modified project.json artifact propagate through pipeline stages

After the pipeline gets triggered from CTA via the notify_cta_project, the project.json gets produced as a new artifact here:

https://gitlab.cern.ch/cta/CTA/-/jobs/59171764

IN the next CI pipeline stages, e.g. in the test_client.sh which in this case ran on ctadev12 we see the default CTA project.json being used instead:

[cirunner@ctadev12 CTA]$ less project.json
[cirunner@ctadev12 CTA]$ pwd
/home/cirunner/builds/t3_6A3YKT/0/cta/CTA
[cirunner@ctadev12 CTA]$ grep eosImage project.json
    "eosImageRepository": "gitlab-registry.cern.ch/dss/eos/eos-ci",
    "eosImageTag": "5.3.14.el9",

This must be fixed.