udev: exclude DRBD from block device ownership event locking

udev: exclude DRBD from block device ownership event locking

It does not make sense for udev to even open DRBD block devices
(/dev/drbdX). It is on one hand not necessary as DRBD is controlled by
something else in the stack (e.g., pacemaker), and it even can get
cumbersome in various scenarios (e.g., DRBD9 auto-promote).

Closes: #9371
Signed-off-by: Roland Kammerer <roland.kammerer@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>