Add mainline TEST_MAPPING to run S module on R base image

Bug: 169443762
Test: presubmit
Change-Id: Id22217964450c14b4ef09b76a4366e66191c347d
diff --git a/wifi/tests/AndroidTest.xml b/wifi/tests/AndroidTest.xml
index 34e2e3a..2cdaddb 100644
--- a/wifi/tests/AndroidTest.xml
+++ b/wifi/tests/AndroidTest.xml
@@ -20,6 +20,8 @@
 
     <option name="test-suite-tag" value="apct" />
     <option name="test-tag" value="FrameworksWifiApiTests" />
+    <option name="config-descriptor:metadata" key="mainline-param"
+            value="com.google.android.wifi.apex" />
     <test class="com.android.tradefed.testtype.AndroidJUnitTest" >
         <option name="package" value="android.net.wifi.test" />
         <option name="runner" value="androidx.test.runner.AndroidJUnitRunner" />