Merge branch '436529-replace-partitioned-fks' into 'master'

Replace FKs for p_ci_stages and p_ci_pipeline_variables

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/159725



Merged-by: Adam Hegyi <ahegyi@gitlab.com>
Approved-by: Tianwen Chen <tchen@gitlab.com>
Approved-by: Adam Hegyi <ahegyi@gitlab.com>
Reviewed-by: Tianwen Chen <tchen@gitlab.com>
Co-authored-by: Marius Bobin <mbobin@gitlab.com>