Add not null constraint to deploy token project_id and group_id

What does this MR do and why?

Add not null constraint to deploy token project_id and group_id. The previous attempt to add this constraint was skipped due to invalid records being present in staging. These are being fixed by !206777 (merged), which needs to be merged (and deployed) first.

References

#477395 (closed)

How to validate

Once the migration in !206777 (merged) has been deployed we need to double check there are no invalid records remaining on staging. We can check this via Teleport with the following query, and we expect to see a result of zero records:

select count(*) from deploy_tokens where project_id is null and group_id is null;

We don't need to perform the same checks in production, as this is checked by the testing pipeline.

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