Setting `yarn.downloadBaseUrl = null` got deprecat...

# gradle

[Vampire]

Setting yarn.downloadBaseUrl = null got deprecated in KGP 2.1.
It instructs to use yarn.downloadBaseUrlProperty instead, but that is internal.
😕

[Vampire]

Ah, the deprecation hint is just wrong: https://youtrack.jetbrains.com/issue/KT-77326