Draft: Validate ci_job_variables#project_id constraint
Ref: #463243
What does this MR do and why?
This MR enforces our new not null constraint at the database level to prevent creating records without a project as this is a requirement for Cells1.0.
The backfill has been completed and we don't have any records left without a project_id
.
gitlabhq_dblab=# select count(*) from ci_job_variables where project_id is null;
count
-------
0
(1 row)