Explore memory leaks when a primary on one of backup instances is stopped

There is a high chance of memory leaks if one of the (non-master) primaries is stopped.

The corresponding instance will not be able to order, and requests will not be cleared till the next view change.

Acceptance criteria:

Perform the following tests and report results about memory consumption with memory checks enabled (in particular, the checks for memory usage of our internal queues and structures).

• Disable view change. Stop a primary on 1 backup instance. Run load of 10 writes per second.
• Disable view change. Stop a primary on multiple backup instances. Run load of 10 writes per second.