Remove Salmon and PubSubHubbub (#11205)

* Remove Salmon and PubSubHubbub endpoints

* Add error when trying to follow OStatus accounts

* Fix new accounts not being created in ResolveAccountService

app/workers/scheduler/subscriptions_scheduler.rb

@@ -5,13 +5,5 @@ class Scheduler::SubscriptionsScheduler
 
   sidekiq_options unique: :until_executed, retry: 0
 
-  def perform
-    Pubsubhubbub::SubscribeWorker.push_bulk(expiring_accounts.pluck(:id))
-  end
-
-  private
-
-  def expiring_accounts
-    Account.expiring(1.day.from_now).partitioned
-  end
+  def perform; end
 end