I'm trying to change something in
As you note above you can
make snod to just make the system image without dependencies.
make out/target/product/your-device/system.img which I believe will build a system image plus its dependencies, but nothing else.
make probably won't do what you want, because the Android build system will build everything, even stuff which isn't a dependency - it builds all the other packages just in case they are broken by changes to the APIs.