Allow shell to read default fstab

CTS module CtsFsMgrTestCases (gtest) needs to read fstab.

Fixes: 184850580
Test: CtsFsMgrTestCases on user build
Change-Id: I0f04bb021d8732a1c5f987ba2984da2c98f40653
diff --git a/private/gsid.te b/private/gsid.te
index e6a395a..8a13cb1 100644
--- a/private/gsid.te
+++ b/private/gsid.te
@@ -183,7 +183,10 @@
 } gsi_public_metadata_file:file_class_set ~{ r_file_perms };
 
 # Prevent apps from accessing gsi_metadata_file_type.
-neverallow appdomain gsi_metadata_file_type:dir_file_class_set *;
+neverallow {
+    appdomain
+    -shell
+} gsi_metadata_file_type:dir_file_class_set *;
 
 neverallow {
     domain