Avoid creating a Network with INetd.LOCAL_NET_ID

INetd.LOCAL_NET_ID cannot be referred to by system SDK. To make the
MdnsSocketProvider built with system SDK, the reference to
INetd.LOCAL_NET_ID must be removed.

This network is created in MdnsSocketProvider.java and propagated
through MdnsSocketProvider.java -> MdnsMultinetworkSocketClient.java ->
MdnsDiscoveryManager.java -> MdnsServiceTypeClient.java ->
NsdService.java. In NsdService.java, it was used in
handleMdnsDiscoveryManagerEvent() -> buildNsdServiceInfoFromMdnsEvent()
-> setServiceNetworkForCallback(). The setServiceNetworkForCallback() is
updated to handle the NETID_UNSET the same as LOCAL_NET_ID.

Test: atest CtsNetTestCases FrameworksNetTests
Bug: 272392042
Change-Id: I07c573948e9dc6249325f0733807bb7a7ffc281c

service-t/src/com/android/server/NsdService.java

@@ -1106,9 +1106,12 @@ public class NsdService extends INsdManager.Stub {
                 final String serviceName = serviceInfo.getServiceInstanceName();
                 final NsdServiceInfo servInfo = new NsdServiceInfo(serviceName, serviceType);
                 final Network network = serviceInfo.getNetwork();
+                // In MdnsDiscoveryManagerEvent, the Network can be null which means it is a
+                // network for Tethering interface. In other words, the network == null means the
+                // network has netId = INetd.LOCAL_NET_ID.
                 setServiceNetworkForCallback(
                         servInfo,
-                        network == null ? NETID_UNSET : network.netId,
+                        network == null ? INetd.LOCAL_NET_ID : network.netId,
                         serviceInfo.getInterfaceIndex());
                 return servInfo;
             }