Change domain blocks to immediately mark accounts as suspended

Rather than doing so sequentially, account after account, while cleaning
their data. This doesn't change much about the time the block takes to
complete, but it immediately prevents interaction with the blocked domain,
while up to now, it would only be guaranteed when the process ends.

app/services/block_domain_service.rb

@@ -34,7 +34,8 @@ def silence_accounts!
   end
 
   def suspend_accounts!
-    blocked_domain_accounts.without_suspended.reorder(nil).find_each do |account|
+    blocked_domain_accounts.without_suspended.in_batches.update_all(suspended_at: @domain_block.created_at)
+    blocked_domain_accounts.where(suspended_at: @domain_block.created_at).reorder(nil).find_each do |account|
       SuspendAccountService.new.call(account, reserve_username: true, suspended_at: @domain_block.created_at)
     end
   end