Add periodic removal of older thumbnails for preview cards (#11304)

app/workers/scheduler/preview_cards_cleanup_scheduler.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+class Scheduler::PreviewCardsCleanupScheduler
+  include Sidekiq::Worker
+
+  sidekiq_options unique: :until_executed, retry: 0
+
+  def perform
+    Maintenance::UncachePreviewWorker.push_bulk(recent_link_preview_cards.pluck(:id))
+    Maintenance::UncachePreviewWorker.push_bulk(older_preview_cards.pluck(:id))
+  end
+
+  private
+
+  def recent_link_preview_cards
+    PreviewCard.where(type: :link).where('updated_at < ?', 1.month.ago)
+  end
+
+  def older_preview_cards
+    PreviewCard.where('updated_at < ?', 6.months.ago)
+  end
+end