Create sepolicy for allowing system_server rw in /metadata/staged-install

Bug: 146343545
Test: presubmit
Change-Id: I4a7a74ec4c5046d167741389a40da7f330d4c63d
Merged-In: I4a7a74ec4c5046d167741389a40da7f330d4c63d
(cherry picked from commit be5c4de29fe7ead7fa55ab6865d9f397dd179a30)
diff --git a/private/system_server.te b/private/system_server.te
index 4a3a538..e71e847 100644
--- a/private/system_server.te
+++ b/private/system_server.te
@@ -1131,6 +1131,10 @@
 allow system_server password_slot_metadata_file:dir rw_dir_perms;
 allow system_server password_slot_metadata_file:file create_file_perms;
 
+# Allow system server rw access to files in /metadata/staged-install folder
+allow system_server staged_install_file:dir rw_dir_perms;
+allow system_server staged_install_file:file create_file_perms;
+
 # Allow init to set sysprop used to compute stats about userspace reboot.
 set_prop(system_server, userspace_reboot_log_prop)