[sinttest] Refactoring XEP-0045 test for default roles
When testing for default role assignment based on affiliation, depending on the 'adminGranted' callback is dangerous, as this callback appears to be only invoked when the affected occupant has already joined the room.
The exact occupant count isn't something that these tests need to assert either.
This commit changes the test implementations to proceed when all expected occupants have been detected by the user performing the change.
These changes combined intend to make the tests more robust, with regards to the order in which several events are fired (which might be unexpeced, given threading implementation in server (clusters) and Smack stanza handling.
