AvailableNetworkNotifier: Use SYSTEM_UID for ONA connection

WIFI_UID does not have NETWORK_SETTINGS permission. So, use SYSTEM_UID
which is probably more apt anyway since this is what settings app uses (User
clicking on the notification is meant to simulate connecting to the
network from wifi picker).

Bug: 155116995
Test: atest com.android.server.wifi
Test: Manual verification of connection using ONA notification.
Change-Id: I5f87f2d14a8180f02a50269515702809426a81ff
2 files changed