tests: Stop connection at the end of monitor_iface_unknown_sta

Do not leave the station trying to connect at the end of the test case
since that can have an effect to the following test case. Such sequences
should be tested in test cases that are specifically designed for that
rather than randomly between test cases.

Signed-off-by: Jouni Malinen <j@w1.fi>

tests/hwsim/test_monitor_interface.py

@@ -76,3 +76,4 @@ def test_monitor_iface_unknown_sta(dev, apdev):
     ev = dev[0].wait_event(["CTRL-EVENT-DISCONNECTED"], timeout=5)
     if ev is None:
         raise Exception("No disconnection")
+    dev[0].request("DISCONNECT")