Fix partition_id for ci_job_variables

⚠ We need to fix ci_builds & ci_pipelines in production before introducing this FK

---

Ref: #387301 (closed)

What does this MR do and why?

This MR fixes invalid ci_job_variables records in production and sets the partition_id to *100.

Database

We have around 62K records to fix.

select count(*) from ci_job_variables where partition_id = 101;

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.