Replace FKs for p_ci_job_artifacts

Ref: #439028 (closed)

What does this MR do and why?

This MR creates FKs pointing to p_ci_job_artifacts now that we partitioned Ci::JobArtifact as they don't exist for the moment.

It creates the constraints and mark them as invalid as they will be validated over the weekend on gitlab.com.

Why are we doing this?

Now the we successfully partitioned ci_job_artifacts we need to make sure the referenced FKs are targeting our new routing table.

https://docs.gitlab.com/ee/development/database/partitioning/list.html#step-7---re-point-foreign-keys-to-parent-table