Mark runner columns as ignored

What does this MR do and why?

This MR follows the guidance in https://docs.gitlab.com/ee/development/database/avoiding_downtime_in_migrations.html#ignoring-the-column-release-m to start removing columns marked for removal in %17.0 . follow-up up issues:

• Drop deprecated columns from ci_runners (#458721)
• Remove ignored columns rule from Ci::Runner (#458722)

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