Maximum number of times the pooled session may be handed out before the pool restarts
it on the next request.
This counts Jenkins-level operations (each acquisition of the shared session by
a clone/power-on/snapshot/delete/etc. step) - not the number of individual vCenter SOAP
calls those operations make internally, and not background health checks.
The limit is enforced atomically: an operation that has already acquired the session
always finishes on it, and only the next request triggers the restart, so a
single logical operation is never interrupted mid-way.
This provides a use-count-based rotation independent of how long the session has been
alive.
Set to 0 to never restart based on use count.