Add support for /product-services partition.

This CL is largely and adaptation of
Ie996def20e25dc1afe0c74af2096af844934b2dc

Bug: 80741439
Test: Successfully built product-services.img with one module in it, and
flashed on device. Also successfully built image with
/system/product-services and no dedicated /product-services partition.

Change-Id: I1046dfe19bf874da929c9131b76a1f85422fbb80
Merged-In: I1046dfe19bf874da929c9131b76a1f85422fbb80
diff --git a/init/property_service.cpp b/init/property_service.cpp
index d1c427d..c0d811f 100644
--- a/init/property_service.cpp
+++ b/init/property_service.cpp
@@ -691,6 +691,7 @@
         }
     }
     load_properties_from_file("/product/build.prop", NULL);
+    load_properties_from_file("/product-services/build.prop", NULL);
     load_properties_from_file("/odm/default.prop", NULL);
     load_properties_from_file("/vendor/default.prop", NULL);