[GarageMode] Adding GarageModeTestApp to default test apps list

Test: Manual
Bug: 111353018

Change-Id: I870de886b7555eafdc3cc0e6f14caa66946a5d5e
(cherry picked from commit 24661778cc15cb8a78f3180dd62e02eb19444d82)
diff --git a/car_product/build/car.mk b/car_product/build/car.mk
index 6606c39..ff562e5 100644
--- a/car_product/build/car.mk
+++ b/car_product/build/car.mk
@@ -41,6 +41,7 @@
     android.car.cluster.loggingrenderer \
     DirectRenderingClusterSample \
     com.android.car.powertestservice \
+    GarageModeTestApp \
 
 # SEPolicy for test apps / services
 BOARD_SEPOLICY_DIRS += packages/services/Car/car_product/sepolicy/test