ISPN-4490 Members can miss the rebalance cancellation on coordinator change

Simulate the rebalance cancellation in StateTransferManagerImpl.
ISPN-4496 EncryptProtocolIT shouldn't check passwords via JMX
Replace ignore tests with empty test to avoid false alarms
ISPN-3938 AdvancedAsyncCacheLoader.process() concurrency issues

Simplify ExecutorAllCompletionService to track the tasks itself instead of
using an ExecutorCompletionService.