ISPN-2658 Update serialized count MarshalledValue test

https://issues.jboss.org/browse/ISPN-2658

* The test used to pass due to lack of clearing between test methods and in fact even in older releases, if you run the test method individually, it would fail. So, the test was passing due to the effect of other test methods.
* The test has now been changed with the correct expectations.