auto-t: wpas.py: don't require strict match on wait_for_event

wait_for_event was checking the event string presence in the rx_data
array which meant the event string had to match perfectly to any
received events. This poses problems with events that include additional
information which the caller may not be able to know or does not care
about. For example:

DPP-RX src=02:00:00:00:02:00 freq=2437 type=11

Waiting for this event previously would require the caller know src, freq,
and type. If the caller only wants to wait for DPP-RX, it can now do that.

autotests/util/wpas.py

@@ -70,7 +70,8 @@ class Wpas:
         while True:
             context.iteration(may_block=True)
 
-            if event in self._rx_data:
+            for e in self._rx_data:
+                if event in e:
                     GLib.source_remove(timeout)
                     return self._rx_data