Fix Geo migration spec

What does this MR do and why?

The test was failing in CI because the Geo CI job artifact registry had cached the newer state of the columns that no longer had the success column. migrate! doesn't reset the column information. This change resets the state so that the migration spec passes.

MR acceptance checklist

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How to set up and validate locally

To reproduce the failure, run:

CI=true bundle exec rspec ./ee/spec/migrations/geo/migrate_ci_job_artifacts_to_separate_registry_spec.rb

From https://gitlab.com/gitlab-org/gitlab/-/issues/462487#note_1911223919