system_server: neverallow sysfs file access.

Bug: 65643247
Test: build aosp_sailfish-userdebug
Test: build walleye-userdebug from internal
Change-Id: Ic7a212ce226dcfa4b363ed1acd3b2a249cee576b

private/domain.te

@@ -45,7 +45,6 @@ full_treble_only(`
     -priv_app
     -storaged
     -system_app
-    -system_server
     -ueventd
     -update_verifier
     -vold