tests: Make FST tests aware of unconditional station's MB IE exposure

tests: Make FST tests aware of unconditional station's MB IE exposure

This syncs the test cases with the implementation change in station's MB
IE creation. FST tests should expect MB IE regardless of the station
connection state and whether the current connection is FST-enabled or
not. This fixes the follow test cases that started reporting failures
with the previous commit change in src/fst/fst_group.c:
fst_disconnect_1_of_2_stas_from_non_fst_ap
fst_sta_connect_to_non_fst_ap
fst_second_sta_connect_to_non_fst_ap
fst_disconnect_2_of_2_stas_from_non_fst_ap
fst_second_sta_connect_to_fst_ap
fst_disconnect_1_of_2_stas_from_fst_ap

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