QA updated to test instance removing when sec. is offline

Added test checking that it is possible to remove an instance with drbd
disk when non-primary node is offline.

Signed-off-by: Agata Murawska <agatamurawska@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>
Reviewed-by: René Nussbaumer <rn@google.com>