Remove ignored_column from Ci::Runner

What does this MR do and why?

This MR implements the final stage (https://docs.gitlab.com/ee/development/database/avoiding_downtime_in_migrations.html#removing-the-ignore-rule-release-m2) of removing the columns that were ignored in %17.0 by !151343 (closed).

Closes #458722 (closed)

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