Migrate bootable/recovery to androidx.test

See go/jetpack-test-android-migration

Test: make checkbuild
Change-Id: I0740a2205e6b3893ba292cd841592ea85071eefb
diff --git a/updater_sample/tests/src/com/example/android/systemupdatersample/util/PayloadSpecsTest.java b/updater_sample/tests/src/com/example/android/systemupdatersample/util/PayloadSpecsTest.java
index 0308693..9931e7b 100644
--- a/updater_sample/tests/src/com/example/android/systemupdatersample/util/PayloadSpecsTest.java
+++ b/updater_sample/tests/src/com/example/android/systemupdatersample/util/PayloadSpecsTest.java
@@ -22,9 +22,10 @@
 import static org.junit.Assert.assertEquals;
 
 import android.content.Context;
-import android.support.test.InstrumentationRegistry;
-import android.support.test.filters.SmallTest;
-import android.support.test.runner.AndroidJUnit4;
+
+import androidx.test.InstrumentationRegistry;
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
 
 import com.example.android.systemupdatersample.PayloadSpec;
 import com.example.android.systemupdatersample.tests.R;