Add mcts tag to MainlineCTS networking test modules which is used for build all the mainline CTS tests.

Bug: 316436957

Change-Id: I0e7ab773075fb0dfd154dde45a710d1c1823c914
diff --git a/tests/cts/net/Android.bp b/tests/cts/net/Android.bp
index 9310888..3d53d6c 100644
--- a/tests/cts/net/Android.bp
+++ b/tests/cts/net/Android.bp
@@ -131,6 +131,7 @@
         "cts",
         "general-tests",
         "mts-tethering",
+        "mcts-tethering",
     ],
 }