Do not apply subsequent updates if one failed.

Sequel::Rollback gets caught by Sequel.transaction block so all
subsequent updates were applied. Now we just mark update as failed and re-raise
the exception to end the process.

Apply task won't run and will send an error message if there are any
failed updates, see https://github.com/alphagov/trade-tariff-backend/blob/cd87056e7a0216560a3eec6497c8faace15f65c5/lib/tariff_synchronizer.rb#L105.