ISPN-4873 Statetransfer thread pool deadlock

* Update LargeClusterStressTest to create a large number of caches
* Make StateRequestCommand implement TopologyAffectedCommand
ISPN-4941 Re-enabling rebalancing should not start a rebalance for a cache
in degraded mode
IgnoreReturnValueForConditionalOperationsTxTest wasn't really testing transactional mode.