Vendor or product extra apps/files can't be added to the generic system
image. Like below error:
```
FAILED:
build/make/core/artifact_path_requirements.mk:31: warning: vendor/google/products/cf_x86_64_phone.mk produces files inside build/make/target/product/generic_system.mks artifact path requirement. Consider adding this file to the system_ext or product partition instead. Confused? Ch
eck out go/artifact-error.
Offending entries:
system/etc/permissions/privapp-permissions-com.android.threadnetwork.demoapp.xml
system/priv-app/ThreadNetworkDemoApp/ThreadNetworkDemoApp.apk
```
Bug: 330097284
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:4c39c8f63edfa55edbd84a8473887df17ffe52fd)
Merged-In: I1b3723c12da44d80555aa35a86b9bae722845cb3
Change-Id: I1b3723c12da44d80555aa35a86b9bae722845cb3
184b400f8f