Cleanup DRBD 8.4 devices properly during QA

QA cleans up DRBD 8.4 devices via drbdsetup, which currently only worked
for DRBD 8.3. This (rather ugly) command makes sure that DRBD 8.4
devices are cleaned up as well.

Signed-off-by: Thomas Thrainer <thomasth@google.com>
Signed-off-by: Michele Tartara <mtartara@google.com>
Reviewed-by: Michele Tartara <mtartara@google.com>