tests: Dump control interface sockets during FST operations

tests: Dump control interface sockets during FST operations

This makes it less likely to hit issues with running out of control
interface TX queue when running multiple FST test in a row. Number of
the FST operation sequences seemed to leave quite a few event messages
pending in one of the attached control interface sockets for wlan5 which
could result in test failure if the buffer space ran out and some of the
wpa_supplicant events were not delivered.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>