Remove NetdService usage from EthernetTracker.

Ethernet service related files are going to be moved into Connectivity
module. So, NetdService won't be visible to EthernetTracker since it's
a hidden class. Alternatively, get the INetd instance from system
service instead.

Bug: 210586283
Test: atest FrameworksNetTests
Test: atest EthernetServiceTests
Change-Id: Iea021ac25cbe4b8836fdab2cd6b4bd3ead5bf725

service-t/src/com/android/server/ethernet/EthernetTracker.java

@@ -40,7 +40,6 @@ import android.os.ServiceManager;
 import android.text.TextUtils;
 import android.util.ArrayMap;
 import android.util.Log;
-import android.net.util.NetdService;
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.IndentingPrintWriter;
@@ -124,7 +123,9 @@ final class EthernetTracker {
         // The services we use.
         IBinder b = ServiceManager.getService(Context.NETWORKMANAGEMENT_SERVICE);
         mNMService = INetworkManagementService.Stub.asInterface(b);
-        mNetd = Objects.requireNonNull(NetdService.getInstance(), "could not get netd instance");
+        mNetd = INetd.Stub.asInterface(
+                (IBinder) context.getSystemService(Context.NETD_SERVICE));
+        Objects.requireNonNull(mNetd, "could not get netd instance");
 
         // Interface match regex.
         updateIfaceMatchRegexp();