The simplest way to test this was to create a new AP, where
max_num_sta=1. This only allows a single STA to connect to this AP.
We connect a device to this AP, then try and connect with another.
This results in hostapd failing with DENIED_NO_MORE_STAS, which will
cause a temporary blacklist. We can then disconnect both devices,
and reconnect the device that previously got denied. If it connects
then we know the blacklist only persisted for that earlier connection.
