Replace "mts" with "mts-tethering".

Bug: 203466102
Test: build locally and verified contents
Change-Id: I7cccb54c0ad1a3bd8da0bcb7ad6474aa1e734299
diff --git a/Tethering/tests/unit/Android.bp b/Tethering/tests/unit/Android.bp
index 0eb682b..85169f9 100644
--- a/Tethering/tests/unit/Android.bp
+++ b/Tethering/tests/unit/Android.bp
@@ -97,7 +97,7 @@
     platform_apis: true,
     test_suites: [
         "device-tests",
-        "mts",
+        "mts-tethering",
     ],
     defaults: ["TetheringTestsDefaults"],
     compile_multilib: "both",