betterbug: Update selinux policy for betterbug Update startup_bugreport_requested property to vendor_public for betterbug to access. Bug: 237287659 Test: Load Betterbug for accessing startup bugreport reason property Signed-off-by: George Lee <geolee@google.com> Change-Id: Idc07e3f4ce425c0167654743fbe1ad8b7ece5e15