Fix Wi-Fi tips disappeared issue in airplane mode

- The Wi-Fi state will not be called back in the airplane mode, need to
call onWifiStateChanged() to update the initial state of the UI.

- Screenshot:
  https://screenshot.googleplex.com/8XJXAGTS5FetGQi

Bug: 173179150
Test: manual test
make RunSettingsRoboTests ROBOTEST_FILTER=WifiSettingsTest

Change-Id: I6d9eae26d6def3bff942f8b01e2ddb453327a7de