Fix test for new behaviour of 'joining' flag
Fix test for new behaviour of 'joining' flag

It's no longer reset when the join request completes, so don't
assert it. (The important test is later, asserting that the room
object is non-null).

vector-im/riot-web,martindale/vector,vector-im/vector-web,vector-im/riot-web,martindale/vector,vector-im/riot-web,vector-im/riot-web,vector-im/vector-web,vector-im/vector-web,vector-im/vector-web,vector-im/riot-web,vector-im/riot-web,vector-im/vector-web