Fix CDN downloads not always calling GetCdnConfigRequest (#222)
Fix CDN downloads not always calling GetCdnConfigRequest (#222)

On previous tests, Telegram didn't return information about CDNs
on the initial GetConfigRequest. However, it may do so, and it's
necessary to call GetCdnConfigRequest even when a second call to
GetConfigRequest isn't required.

LonamiWebs/Telethon,LonamiWebs/Telethon,LonamiWebs/Telethon,andr-04/Telethon,LonamiWebs/Telethon,expectocode/Telethon