[bug#57675] [PATCH v8 RESEND 0/7] gnu: telegram-desktop: Update to 4.2.0.

[Hilton Chain]

>Is there a *good* reason for the intermediate step?
No....

>Also, the %telegram-version was so that we can update the submodules
>(whose hashes I assume change with updated telegrams) more easily.  Is
>there a better versioning scheme for those?
Not all submodules need updating when new releases out.

Another approach is just cloning recursively and remove all sources within 
ThirdParty folder via snippet, then only tracking version changes of these 
removed ones (or unbundle them when applicable).