ISPN-4569 Inserting into cache with indexing fails for XA transactions

* Use the BatchModeTransactionManager for the cluster registry cache.
* Suspend ongoing transactions during cluster registry cache operations,
  in case another cache also uses the same TM.
ISPN-4436 Karaf is stucked when running iOSGI integration tests
ISPN-4601 DirectoryLoaderAdaptor computes the auto-chunk factor applying wrong rounding
ISPN-4436 Karaf stucked when running iOSGI integration tests on IBM JDK

Upgrade the PAX EXAM version in the server integration module also.
IgnoreReturnValueForConditionalOperationsTxTest wasn't really testing transactional mode.