Fix multiple top level classes rubocop error

Having things defined in the top level of files that don't match the class names can break the autoloader and lead to odd behaviour.

I've merged the two uses of ConcurrencyExceededForSchool errors since they both refer to students.

Author: zetter-rpf

app/controllers/api/school_students_controller.rb

@@ -82,7 +82,7 @@ def create_batch
     # should assume the entire student import has failed.
     def enqueue_batches(students)
       # Raise if a batch is already in progress for this school.
-      raise ConcurrencyExceededForSchool if @school.import_in_progress?
+      raise CreateStudentsJob::ConcurrencyExceededForSchool if @school.import_in_progress?
 
       @batch = GoodJob::Batch.new(description: @school.id)
       @batch.enqueue do

app/jobs/create_students_job.rb

@@ -1,8 +1,8 @@
 # frozen_string_literal: true
 
-class ConcurrencyExceededForSchool < StandardError; end
-
 class CreateStudentsJob < ApplicationJob
+  class ConcurrencyExceededForSchool < StandardError; end
+
   retry_on StandardError, wait: :polynomially_longer, attempts: 3 do |_job, e|
     Sentry.capture_exception(e)
     raise e

lib/concepts/school_student/create_batch.rb

@@ -3,15 +3,13 @@
 module SchoolStudent
   class Error < StandardError; end
 
-  class ConcurrencyExceededForSchool < StandardError; end
-
   class CreateBatch
     class << self
       def call(school:, school_students_params:, token:)
         response = OperationResponse.new
         response[:job_id] = create_batch(school, school_students_params, token)
         response
-      rescue ConcurrencyExceededForSchool => e
+      rescue CreateStudentsJob::ConcurrencyExceededForSchool => e
         response[:error] = e
         response[:error_type] = :job_concurrency_error
         response