sepolicy: remove redudant rule for symlinks in /vendor/app

All accesses to /vendor/app within platform include permissions to read
symlinks in the location. This rule is redundant now.

Bug: 36806861
Test: Boot sailfish and find no denials for 'vendor_app_file'

Change-Id: Ic17a67521cff6717d83b78bb4ad8e21e772f6d4f
Signed-off-by: Sandeep Patil <sspatil@google.com>