nixosTests.networking.virtual: fix with networkd

We only need to wait for network.target to get up, and the
network-addresses-${interfaceName} units are scripted networking only.

(cherry picked from commit a501abd5499d8f82f0991a7b78bcbc4169b0537f)
ZHF: #80379
Fix a failing test.

nixos/tests/networking.nix

@@ -471,7 +471,7 @@ let
 
         with subtest("Wait for networking to come up"):
             machine.start()
-            machine.wait_for_unit("network-online.target")
+            machine.wait_for_unit("network.target")
 
         with subtest("Test interfaces set up"):
             list = machine.succeed("ip tuntap list | sort").strip()
@@ -486,7 +486,7 @@ let
             """.format(
                 list, targetList
             )
-
+        '' + optionalString (!networkd) ''
         with subtest("Test interfaces clean up"):
             machine.succeed("systemctl stop network-addresses-tap0")
             machine.sleep(10)