[Thread] add CtsThreadNetworkTestCases to mcts-tethering

Background: go/mcts-design

Bug: 327091762
Change-Id: I5c4f7c33579a84626bcc3f662b9658c646eefbf5

thread/tests/cts/Android.bp

@@ -32,6 +32,7 @@ android_test {
     test_suites: [
         "cts",
         "general-tests",
+        "mcts-tethering",
         "mts-tethering",
     ],
     static_libs: [