Skip some methods in BatchedRemoveStatusService when account is nil (#10095)

* Skip some methods in BatchedRemoveStatusService when account is nil

Sometimes `bin/tootctl accounts cull` fails with below error:

undefined method `followers_for_local_distribution' for nil:NilClass (NoMethodError)

This commit makes BatchedRemoveStatusService to skip below methods when
`account` is nil:

- unpush_from_home_timelines()
- unpush_from_list_timelines()
- batch_stream_entries()

* Fix rubocop error: Use `next` to skip iteration.

app/services/batched_remove_status_service.rb

@@ -35,6 +35,8 @@ class BatchedRemoveStatusService < BaseService
     statuses.group_by(&:account_id).each_value do |account_statuses|
       account = account_statuses.first.account
 
+      next unless account
+
       unpush_from_home_timelines(account, account_statuses)
       unpush_from_list_timelines(account, account_statuses)