vndservicemanager: use selinux_vendor_log_callback

This function only uses vendor APIs even on non-VNDK devices. This
is to support the usecase of vndservicemanager on a legacy device
which has the VNDK disabled.

Bug: 113083310
Test: boot up device and see usage of /system/etc/event-log-tags
    denials go away.

Change-Id: I0fd86cce303bf169f6d5b1b873221302e5b260b1