Draft: Initialize the conversion for p_ci_builds pipeline_id related

What does this MR do and why?

Initialize the conversion for p_ci_builds pipeline_id related

This is the first step to convert pipeline_id related to bigint for:

• p_ci_builds.auto_canceled_by_id
• p_ci_builds.commit_id
• p_ci_builds.upstream_pipeline_id

See https://docs.gitlab.com/ee/development/database/avoiding_downtime_in_migrations.html#initialize-the-conversion-and-start-migrating-existing-data-release-n

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Before	After

How to set up and validate locally

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

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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

Related to #412873 (closed)