Update import_failures sharding

What does this MR do and why?

As part of the cells preparation, the import & integrate team needs to set the sharding key for a few tables, and clean up any old data as well as setting appropriate foreign keys and database checks. The original MR to do this has been broken up into individual MRs per table as suggested during the review process, to make reviewing easier.

In this MR, we ensure the ImportFailure gets an organization_id assigned to it if no project_id or group_id exists. It also sets those 3 columns to the sharding keys and adds a check to ensure they are not all null.

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Related to #463854 (closed)