Adding the option to assign a poll to a poll recount factory meant we
didn't need to create so much data.
Also note we're removing the `create(:poll_voter, origin: "booth")`
code, since it isn't used in the stats calculations.
The factories were creating strange database relations:
* The voter belonged to a poll, to a booth and to an officer
* The booth belonged to a different poll
* The officer belonged to a different booth
The code uses an unusual syntax because the following code:
association :booth_assignment,
factory: :poll_booth_assignment,
poll: poll
Would generate the following error:
ActiveRecord::AssociationTypeMismatch: Poll(#46976420451940) expected,
got FactoryBot::Declaration::Implicit
