Loosen system app data neverallows

We don't want to prevent access from vendor platform apps to system app
data. The issue with the referencing system_app explicitly in
neverallows is that vendor platform apps which need sandboxes similar to
system_app cannot be placed under system_app without modifying the
policy for all platform apps.

Test: mmm system/sepolicy
Change-Id: Ic0052602c31be4d74b02eeea129e2d8bfbd9c8d3

public/domain.te

@@ -656,10 +656,17 @@ neverallow installd system_data_file:file ~{ r_file_perms relabelfrom unlink };
 # respect system_app sandboxes
 neverallow {
   domain
-  -system_app # its own sandbox
+  -appdomain # finer-grained rules for appdomain are listed below
   -system_server #populate com.android.providers.settings/databases/settings.db.
   -installd # creation of app sandbox
 } system_app_data_file:dir_file_class_set { create unlink open };
+neverallow {
+  isolated_app
+  untrusted_app_all # finer-grained rules for appdomain are listed below
+  ephemeral_app
+  priv_app
+} system_app_data_file:dir_file_class_set { create unlink open };
+
 
 # Services should respect app sandboxes
 neverallow {