Issues with storing and submitting of scans

[lbarcziova]

From time to time, some of the scans end up with no info in the DB (e.g., https://dashboard.packit.dev/jobs/openscanhub/4480) while the scan is being submitted correctly: https://openscanhub.fedoraproject.org/task/30559/, resulting also in no reporting to the user.

We have previously introduced a mechanism when processing the scans that prevents multiple scans from being stored in our DB for the same Copr build, which is probably related to this issue. Relevant code: https://github.com/packit/packit-service/blob/2c4667785f9d0f39a532d52d1cc54da44998eba6/packit_service/worker/helpers/open_scan_hub.py#L96-L138