runas_app domain is used by lldb/ndk-gdb/simpleperf to debug/profile
debuggable apps. But it misses permissions to ptrace app processes and
read /proc/<app_pid> directory.

Bug: none
Test: build and boot marlin.
Test: run lldb and simpleperf on apps with target sdk version 24-29.
Change-Id: I9e6f940ec81a8285eae8db3b77fb1251a25dedd0