Fix handling of "android.test.mock" in class loader context.

Mimick the way PackageManager handles it at runtime: do add it to class
loader context for apps with targetSdkVersion < 30, but only if
"android.test.runner" is used. Previously it was not added at all.

Test: lunch aosp_cf_x86_phone-userdebug && m
Bug: 132357300
Change-Id: I4c06635277ab13e21069b9fa0b46eb6a2547dfdd
diff --git a/java/app_test.go b/java/app_test.go
index 98945da..f2e4349 100644
--- a/java/app_test.go
+++ b/java/app_test.go
@@ -2838,6 +2838,7 @@
 	}
 
 	// Test conditional context for target SDK version 30.
+	// "android.test.mock" is absent because "android.test.runner" is not used.
 	if w := `--target-classpath-for-sdk 30` +
 		` /system/framework/android.test.base.jar `; !strings.Contains(cmd, w) {
 		t.Errorf("wanted %q in %q", w, cmd)
@@ -2852,8 +2853,10 @@
 	}
 
 	// Test conditional context for target SDK version 30.
+	// "android.test.mock" is present because "android.test.runner" is used.
 	if w := `--target-classpath-for-sdk 30` +
-		` /system/framework/android.test.base.jar `; !strings.Contains(cmd, w) {
+		` /system/framework/android.test.base.jar` +
+		`:/system/framework/android.test.mock.jar `; !strings.Contains(cmd, w) {
 		t.Errorf("wanted %q in %q", w, cmd)
 	}
 }