Clarify use of isDefaultTranslation() to determine if an entity values should be updated.

In #2812811: Use EntityPublishedInterface during moderation of entities to add support beyond nodes I am proposing to remove this code from the handler, it doesn't seem as though it's needed.

I just looked at \Drupal\content_moderation\EntityOperations::entityPresave() and there's no isDefaultTranslation() anymore:

  public function entityPresave(EntityInterface $entity) {
    if (!$this->moderationInfo->isModeratedEntity($entity)) {
      return;
    }

    if ($entity->moderation_state->value) {
      $workflow = $this->moderationInfo->getWorkflowForEntity($entity);
      /** @var \Drupal\content_moderation\ContentModerationState $current_state */
      $current_state = $workflow->getState($entity->moderation_state->value);

      // This entity is default if it is new, a new translation, the default
      // revision, or the default revision is not published.
      $update_default_revision = $entity->isNew()
        || $entity->isNewTranslation()
        || $current_state->isDefaultRevisionState()
        || !$this->moderationInfo->isDefaultRevisionPublished($entity);

      // Fire per-entity-type logic for handling the save process.
      $this->entityTypeManager->getHandler($entity->getEntityTypeId(), 'moderation')->onPresave($entity, $update_default_revision, $current_state->isPublishedState());
    }
  }