Allow vendor_init to getattr vold_metadata_file.

This relaxes the neverallow rule blocking vendor_init from doing
anything to vold_metadata_file.  The rules above it still prevent it
from doing anything other than relabelto and getattr.

Bug: 79681561
Test: Boot device and see no denials.
Change-Id: I1beb25bb9f8d69323c9fee53a140c2a084b12124

prebuilts/api/28.0/public/vold.te

@@ -244,6 +244,7 @@ neverallow {
     domain
     -init
     -kernel
+    -vendor_init
     -vold
     -vold_prepare_subdirs
 } { vold_data_file vold_metadata_file }:notdevfile_class_set *;

public/vold.te

@@ -244,6 +244,7 @@ neverallow {
     domain
     -init
     -kernel
+    -vendor_init
     -vold
     -vold_prepare_subdirs
 } { vold_data_file vold_metadata_file }:notdevfile_class_set *;