Fix remote status fetching for “pure” ActivityPub WEB_ACCOUNT users (#5372)

Remote ActivityPub users that have never been known as OStatus users
(whether or not they support it) will not have a “remote_url” attribute
set. In case they reside on an instance with WEB_DOMAIN ≠ LOCAL_DOMAIN,
the current check did rely on “remote_url” to verify the user's domain.

app/services/fetch_remote_status_service.rb

@@ -40,6 +40,6 @@ class FetchRemoteStatusService < BaseService
   end
 
   def confirmed_domain?(domain, account)
-    account.domain.nil? || domain.casecmp(account.domain).zero? || domain.casecmp(Addressable::URI.parse(account.remote_url).normalized_host).zero?
+    account.domain.nil? || domain.casecmp(account.domain).zero? || domain.casecmp(Addressable::URI.parse(account.remote_url || account.uri).normalized_host).zero?
   end
 end