Update net-tests-utils-host-common tag to "mts-networking"

We use "mts-networking" and not "mts" so that the tests and test dependencies can be properly included in the automated MTS packaging and release (go/mts-packaging).
Instead of tagging tests "mts", we should use "mts-*" where the suffix is one of https://source.corp.google.com/android/test/mts/tools/build/config.mk;l=19.

Test: built locally and verified contents
Bug: 203466102
Change-Id: I5f9bdaf699cfa2525b33178c0e30a6b794b9d5f5
diff --git a/staticlibs/testutils/Android.bp b/staticlibs/testutils/Android.bp
index 9fd30f7..73ddd4b 100644
--- a/staticlibs/testutils/Android.bp
+++ b/staticlibs/testutils/Android.bp
@@ -69,6 +69,6 @@
         "host/**/*.kt",
     ],
     libs: ["tradefed"],
-    test_suites: ["device-tests", "general-tests", "cts", "mts"],
+    test_suites: ["device-tests", "general-tests", "cts", "mts-networking"],
     data: [":ConnectivityChecker"],
 }