district dropdown: fix unit tests that used district_name which is gone.

Author: breville

dashboard/app/controllers/api/v1/pd/workshop_attendance_controller.rb

@@ -50,8 +50,6 @@ def create_teacher(email)
       school: enrollment.school
     }
     teacher = User.find_or_create_teacher(params, current_user)
-    district = District.find_by_name(enrollment.district_name)
-    DistrictsUsers.create!(district_id: district.id, user_id: teacher.id) if district
 
     teacher
   end

dashboard/app/serializers/api/v1/pd/workshop_enrollment_serializer.rb

@@ -1,5 +1,5 @@
 class Api::V1::Pd::WorkshopEnrollmentSerializer < ActiveModel::Serializer
-  attributes :name, :email, :district_name, :school, :user_id
+  attributes :name, :email, :school_district_id, :school, :user_id
 
   def user_id
     object.user ? object.user.id : nil