Disable backfill migration that sets expire_at

What does this MR do and why?

Disables a migration that sets expire_at on old artifacts. This could potentially lead to data loss on artifacts that should be kept.

This migration was introduced in 13.11

Removing this migration is part of the clean up issue #355833 (closed).

Related: #355955 (closed) #355833 (closed)

Following our best practices when disabling a migration.

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