Remove ignore rules for Ci::Pipeline

What does this MR do and why?

Remove ignore rules for Ci::PipelineMessage

See https://docs.gitlab.com/ee/development/database/avoiding_downtime_in_migrations.html#remove-ignore-rules-release-n--3

• Backfill is done at !126645 (merged)
• Index is created at !129201 (merged) and !131108 (merged)
• Foreign key is created at !132609 (merged) and !133162 (merged)
• Columns swap is done at !134597 (merged)
• Cleanup is done at !135542 (merged)

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Before	After

How to set up and validate locally

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MR acceptance checklist

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

Related to #422812 (closed)