Allow shift persistence for rotations to scale

ee/app/models/incident_management/oncall_rotation.rb

@@ -2,6 +2,8 @@
 
 module IncidentManagement
   class OncallRotation < ApplicationRecord
+    include EachBatch
+
     ActivePeriod = Struct.new(:start_time, :end_time) do
       def present?
         start_time && end_time

ee/app/workers/incident_management/oncall_rotations/persist_all_rotations_shifts_job.rb

@@ -15,8 +15,10 @@ module IncidentManagement
       queue_namespace :cronjob
 
       def perform
-        IncidentManagement::OncallRotation.in_progress.pluck(:id).each do |rotation_id| # rubocop: disable CodeReuse/ActiveRecord
-          IncidentManagement::OncallRotations::PersistShiftsJob.perform_async(rotation_id)
+        IncidentManagement::OncallRotation.each_batch do |rotations|
+          rotations.in_progress.ids.each do |id| # rubocop: disable CodeReuse/ActiveRecord
+            IncidentManagement::OncallRotations::PersistShiftsJob.perform_async(id)
+          end
         end
       end
     end