lineage-sdk: Fix traffic stats for tethering and vpn use cases

Problems with current TrafficStats.getTotal[RT]XBytes()
implementation:

* Tethering related traffic is not counted at all.

* If you have a VPN active, stats are double counted.

So change the approach and track traffic on all non-VPN Internet
capable networks since:

* Tethering traffic is included in interface specific stats
  (unlike getTotal*).

* VPN networks are excluded so no longer double counted.

* Works correctly regardless of hotspot "Allow clients to use
  VPNs" hotspot setting.

* Works with simultaneous wifi ap and wifi upstream.
  (WIFI_HIDL_FEATURE_DUAL_INTERFACE = true)

Change-Id: Ic1135f10388b5be427202b092acd1444f94bd2b6