Fix WiFi test:

 -- In environment where there are too many APs, sometimes, the AP will not show in the scan list.
    Part of the reason is due to the change that the scanning on each frequency is shortened to save power.
    to avoid that, change the test to connect without scanning.

 -- Increase the timer to wait for WiFi to be connected

Change-Id: If1a72607b3c7ad13dbbf788607665986eaf5b6b3