priv_app: remove /proc/net access

Remove most of /proc/net access for priv_apps. Files in /proc/net leak
unique device identifiers and side channel information about other app's
network connections.

Access for most third party applications was removed in commit
d78e07cbb717ddd1e87c415cfb0163b504adcf35. This change applies the same
constraints to priv-apps that we apply to normal apps.

Bug: 114475727
Bug: 9496886
Bug: 68016944
Test: policy compiles and device boots
Change-Id: I5c41ba57fcd6b81d72c4f3a40b310d2188fc79c3
1 file changed