Revert "Merge branch '444222-add-sharding-key-not-null-constraint-not-valid' into 'master'"

What does this MR do and why?

Revert "Merge branch '444222-add-sharding-key-not-null-constraint-not-valid' into 'master'" as it's causing errors when updating notes without namespace_id or project_id.

This reverts merge request !204773 (merged)

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