/usr/lib/drbd/unsnapshot-resync-target-lvm.sh is in drbd8-utils 2:8.3.11-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/drbd/snapshot-resync-target-lvm.sh
/usr/lib/drbd/snapshot-resync-target-lvm.sh