DialogSession::clearDeprecatedSessions

static function clearDeprecatedSessions(): string
{
	$days = self::EXPIRES_DAYS;
	$res = NetworkSessionTable::getList([
		'select' => ['ID'],
		'filter' => [
			' (new DateTime())->add("- {$days} days")
		]
	]);
	while ($sess = $res->fetch())
	{
		NetworkSessionTable::delete($sess['ID']);
	}

	return __METHOD__. '();';
}