wifi: Remove redundant WifiMacQueue::MaxQueueSize attribute
Make the WifiMacQueue::MaxQueueSize attribute obsolete, while keeping the default maximum queue size (500 packets), which is different than that of the base class (100 packets).
Make the WifiMacQueue::MaxQueueSize attribute obsolete, while keeping the default maximum queue size (500 packets), which is different than that of the base class (100 packets).