Change image attachment test to use a public resource ID

The test started failing due to resource ID issues when new resources were added likely because test APK resource IDs became out of sync. Because this test doesn't care about what image it's using (just that it's an image), using a public drawable resource is likely more stable and less susceptible to this issue.

Bug: 249302567
Test: atest RemoteInputViewTest
Change-Id: Icb68affe4ecabeb363d97e8517d2acd8e8031d65

packages/SystemUI/tests/src/com/android/systemui/statusbar/policy/RemoteInputViewTest.java

@@ -275,10 +275,9 @@ public class RemoteInputViewTest extends SysuiTestCase {
         EditText editText = view.findViewById(R.id.remote_input_text);
         editText.setText(TEST_REPLY);
         ClipDescription description = new ClipDescription("", new String[] {"image/png"});
-        // We need to use an (arbitrary) real resource here so that an actual image gets attached.
+        // We need to use an (arbitrary) real resource here so that an actual image gets attached
         ClipData clip = new ClipData(description, new ClipData.Item(
-                Uri.parse("android.resource://com.android.systemui/"
-                        + R.drawable.default_thumbnail)));
+                Uri.parse("android.resource://android/" + android.R.drawable.btn_default)));
         ContentInfo payload =
                 new ContentInfo.Builder(clip, SOURCE_CLIPBOARD).build();
         view.setAttachment(payload);