Remove references to networkProviderBatteryChargingStatus flag

The networkProviderBatteryChargingStatus flag has been flipped to true and
the code no longer needs to check it.
This change removes the code checks for the flag.

Bug: 409612054, 249151277
Test:  atest android.net.wifi.sharedconnectivity.cts.SharedConnectivityTest
android.net.wifi.sharedconnectivity.cts.app.HotspotNetworkConnectionStatusTest android.net.wifi.sharedconnectivity.cts.app.HotspotNetworkTest android.net.wifi.sharedconnectivity.cts.app.KnownNetworkConnectionStatusTest android.net.wifi.sharedconnectivity.cts.app.KnownNetworkTest android.net.wifi.sharedconnectivity.cts.app.NetworkProviderInfoTest android.net.wifi.sharedconnectivity.cts.app.SharedConnectivityManagerTest
Flag: com.android.wifi.flags.network_provider_battery_charging_status

Change-Id: I36d15963a30ea35c6bf3c769bf1cd1f69c9f744f