Fix appVisible assertion on OpenAppFromNotificationWarm

The assertion is flaky at the moment because `Splash Screen com.android.server.wm.flicker.testapp` sometimes appear

Fixes: 228878926
Test: atest FlickerTests
Change-Id: I0cb4e32502abe78e6bc4f1624ecd83864560c5b5

tests/FlickerTests/src/com/android/server/wm/flicker/launch/OpenAppTransition.kt

@@ -206,6 +206,10 @@ abstract class OpenAppTransition(protected val testSpec: FlickerTestParameter) {
     protected fun appWindowBecomesVisible_warmStart() {
         testSpec.assertWm {
             this.isAppWindowInvisible(testApp.component)
+                    .then()
+                    .isAppWindowVisible(FlickerComponentName.SNAPSHOT, isOptional = true)
+                    .then()
+                    .isAppWindowVisible(FlickerComponentName.SPLASH_SCREEN, isOptional = true)
                     .then()
                     .isAppWindowVisible(testApp.component)
         }