Prepare ASYNC FK validation on todos#organization_id

What does this MR do and why?

Prepare ASYNC FK validation on todos#organization_id

Addresses #562437

Changelog: other

References

• https://docs.gitlab.com/development/database/foreign_keys/#schedule-the-fk-to-be-validated
• FK (NOT VALID) was added in !204559 (diffs)

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