Backfill ci_runner_machines_687967fa8a partitioned table

What does this MR do and why?

This MR backfills the ci_runner_machines_687967fa8a partitioned table from the ci_runners. It is very similar to the recent !166520 (merged) which did the same for the ci_runners table.

Changelog: added

References

Please include cross links to any resources that are relevant to this MR This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.

• Backfill ci_runner_machines_687967fa8a table (#502934 - closed)
• Backfill ci_runners_e59bb2812d table (!166520 - merged)

MR acceptance checklist

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Screenshots or screen recordings

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Enable the :allow_organization_creation FF:

   Feature.enable(:allow_organization_creation)

2. Go to the shell in your GDK gitlab directory and run bundle exec rake "gitlab:seed:runner_fleet[root, rf-, 500, 100]". This will seed your GDK with some runners and jobs required for testing this MR.

3. Let's run the migration:

   bundle exec rails db:migrate

4. Check http://gdk.test:3000/admin/background_migrations?database=ci to follow the state of the batched migration.

   

5. Compare the number of runner managers in the source table, and the ones in the partitioned table: