Apply MainlineTestModuleController to tethering cts tests

to only run them when com.google.android.tethering is

installed on device. This does not change any existing CTS run.

The logic only applies when the test triggered by mts-tradefed

to make sure it runs appropriate set of tests against the device.

For example, the test will be skipped when running MTS on Q because

tethering and wifi are not on Q devices.

Bug: 154845935
Test: m mts && mts-tradefed run mts-tethering
Change-Id: I9e6bd60982d4ef67538ad506e7008366bbf35363
diff --git a/tests/cts/tethering/AndroidTest.xml b/tests/cts/tethering/AndroidTest.xml
index d0a2bce..e752e3a 100644
--- a/tests/cts/tethering/AndroidTest.xml
+++ b/tests/cts/tethering/AndroidTest.xml
@@ -28,4 +28,8 @@
     <test class="com.android.tradefed.testtype.AndroidJUnitTest" >
         <option name="package" value="android.tethering.cts" />
     </test>
+
+    <object type="module_controller" class="com.android.tradefed.testtype.suite.module.MainlineTestModuleController">
+        <option name="mainline-module-package-name" value="com.google.android.tethering" />
+    </object>
 </configuration>