Fix the consistency of connection status displayed on Wi-Fi card

- Refresh slice in WifiTracker.onConnectedChanged
- Only expose notifySliceChange to child in SliceBackgroundWorker

Fixes: 123270015
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=com.android.settings.wifi.slice
Change-Id: Id5540ebae2746e58e14924665c5e62bf437ebcf0
4 files changed