In SERVER-128710, the logic for applying RetryableError and thus baseBackoffMS to command failures after the IRRL was removed, since it was incorrectly applying them to errors forwarded from backing shards. This inadvertently prevented failCommand failures from automatically receiving the labels and thus baseBackoffMS. We should restore this behavior by applying baseBackoffMS whenever the failpoint overrides the labels to include SystemOverloadedError + RetryableError.