Add e2e automation tests for Gemma3n2b CPU & GPU in Ask Image: T3, T4, T5, T6, T7

PiperOrigin-RevId: 807892326

Author: Google AI Edge Gallery

Android/src/app/src/main/java/com/google/ai/edge/gallery/ui/common/chat/MessageInputText.kt

@@ -281,7 +281,7 @@ fun MessageInputText(
           Box(contentAlignment = Alignment.TopEnd) {
             Image(
               bitmap = image.asImageBitmap(),
-              contentDescription = "",
+              contentDescription = "Camera picked image preview",
               modifier =
                 Modifier.height(80.dp)
                   .shadow(2.dp, shape = RoundedCornerShape(8.dp))