Fix partition_id for ci_stage

Ref: #387301 (closed)

What does this MR do and why?

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

Database

We have around ~565K records to fix.

Following a similar strategy used in !111287 (merged), I choose a default batch size of 3_000 and a sub batch size of 300.

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

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