Fix unbounded recursion in account discovery (v3.5 backport) (#22026)

* Fix trying to fetch posts from other users when fetching featured posts

* Rate-limit discovery of new subdomains

* Put a limit on recursively discovering new accounts

app/workers/activitypub/synchronize_featured_collection_worker.rb

@@ -5,8 +5,10 @@ class ActivityPub::SynchronizeFeaturedCollectionWorker
 
   sidekiq_options queue: 'pull', lock: :until_executed
 
-  def perform(account_id)
-    ActivityPub::FetchFeaturedCollectionService.new.call(Account.find(account_id))
+  def perform(account_id, options = {})
+    options = { note: true, hashtag: false }.deep_merge(options.deep_symbolize_keys)
+
+    ActivityPub::FetchFeaturedCollectionService.new.call(Account.find(account_id), **options)
   rescue ActiveRecord::RecordNotFound
     true
   end