audioserver: drop inet group

The audioserver process is specifically prohibited from accessing the network.
See
7ca6fc8629/private/audioserver.te (91)
line 91

  # Media processing code is inherently risky and thus should have limited
  # permissions and be isolated from the rest of the system and network.
  # Lengthier explanation here:
  # https://android-developers.googleblog.com/2016/05/hardening-media-stack.html
  neverallow audioserver domain:{ tcp_socket udp_socket rawip_socket } *;

Since SELinux doesn't allow audioserver to access tcp/udp sockets, it
doesn't make any sense to have audioserver be in the inet group.

Discovered while reviewing
https://android-review.googlesource.com/c/platform/frameworks/base/+/968497

Similarly, I suspect other groups listed here are also unnecessary and
can be cleaned up in a future commit.

Test: compiles and boots
Change-Id: Ic331f301565aee911de30322dd4c3811529597ee

media/audioserver/audioserver.rc

@@ -2,7 +2,7 @@ service audioserver /system/bin/audioserver
     class core
     user audioserver
     # media gid needed for /dev/fm (radio) and for /data/misc/media (tee)
-    group audio camera drmrpc inet media mediadrm net_bt net_bt_admin net_bw_acct wakelock
+    group audio camera drmrpc media mediadrm net_bt net_bt_admin net_bw_acct wakelock
     capabilities BLOCK_SUSPEND
     ioprio rt 4
     writepid /dev/cpuset/foreground/tasks /dev/stune/foreground/tasks