BulkImports: Add a configuration trait on `bulk_imports` factory

The following discussion from !56242 (merged) should be addressed:

• @arturoherrero started a discussion:

  Same question !56242 (diffs, comment 531318997).

  I think one of the factories seems to need this, maybe we can create a trait or something similar

  https://github.com/thoughtbot/factory_bot/blob/master/GETTING_STARTED.md#traits