Swap the columns for ci_pipeline_messages

What does this MR do and why?

Swap the columns for ci_pipeline_messages

This is the step to swap bigint conversion columns:

• pipeline_id
• pipeline_id_convert_to_bigint

See https://docs.gitlab.com/ee/development/database/avoiding_downtime_in_migrations.html#swap-the-columns-release-n--1

• Backfill is done at !126188 (merged)
• Index is created at !128710 (merged)
• Foreign key is created at !130899 (merged) and !131251 (merged)

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Before	After

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Related to #422798 (closed)