Create multi not null constraint for exports

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.

This wasn't part of the original MR or issue, however, we should ensure we don't have any records without any project or group IDs as we're doing for other tables.

Creates a multi not null constraint for BulkImport::Export on group_id and project_id

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Related to #463854 (closed)