Fix webfinger retries (#4275)

* Do not raise unretryable exceptions in ResolveRemoteAccountService

* Removed fatal exceptions from ResolveRemoteAccountService

Exceptions that cannot be retried should not be raised. New exception
class for those that can be retried (Mastodon::UnexpectedResponseError)

spec/controllers/api/base_controller_spec.rb

@@ -32,7 +32,7 @@ describe Api::BaseController do
       ActiveRecord::RecordInvalid => 422,
       Mastodon::ValidationError => 422,
       ActiveRecord::RecordNotFound => 404,
-      Goldfinger::Error => 422,
+      Mastodon::UnexpectedResponseError => 503,
       HTTP::Error => 503,
       OpenSSL::SSL::SSLError => 503,
       Mastodon::NotPermittedError => 403,