Initialize bigint conversion for p_ci_builds for self-host

What does this MR do and why?

This is to introduce bigint conversion initialization for p_ci_builds for self-host:

• p_ci_builds.auto_canceled_by_id
• p_ci_builds.commit_id
• p_ci_builds.erased_by_id
• p_ci_builds.project_id
• p_ci_builds.runner_id
• p_ci_builds.trigger_request_id
• p_ci_builds.upstream_pipeline_id
• p_ci_builds.user_id

See:

• https://docs.gitlab.com/ee/development/database/avoiding_downtime_in_migrations.html#initialize-the-conversion-and-start-migrating-existing-data-release-n
• !129332 (merged) init is executed on prod, see #422834 (comment 1628412668)

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Before	After

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MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.

Related to #422834 (closed)