Use integers to schedule delayed background migrations

app/workers/background_migration_worker.rb

@@ -17,8 +17,8 @@ class BackgroundMigrationWorker
   # Schedules multiple jobs in bulk, with a delay.
   #
   def self.perform_bulk_in(delay, jobs)
-    now = Time.now.to_f
-    schedule = now + delay.to_f
+    now = Time.now.to_i
+    schedule = now + delay.to_i
 
     raise ArgumentError if schedule <= now
 

spec/migrations/migrate_stage_id_reference_in_background_spec.rb

@@ -6,7 +6,7 @@ describe MigrateStageIdReferenceInBackground, :migration, :sidekiq do
     match do |migration|
       BackgroundMigrationWorker.jobs.any? do |job|
         job['args'] == [migration, expected] &&
-          job['at'].to_f == (delay.to_f + Time.now.to_f)
+          job['at'].to_f == (delay.to_i + Time.now.to_i)
       end
     end