Just a little modification of the files cargrp.dat and popcycle.dat located in \GameFace\Content\OriginalData\GTASA\data. NPCs can now spawn in Glenshit, Phoenix, Euros !
Installation : Create a new folder in \GTA San Andreas - Definitive Edition\Gameface\Content\Paks named ~mods Unzip and just paste the file 100-traffic_P.pak in \GTA San Andreas - Definitive Edition\Gameface\Content\Paks\~mods