Disable waiting animation for native assistant.

Test: build and run locally, stop assistant do not show animation
Bug: b:112229074
Change-Id: I7a669f9a6bf2d11d84a6c3a364c7c4f729068eb1
Reviewed-on: https://chromium-review.googlesource.com/1163841Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580971}

ash/shelf/app_list_button.cc

@@ -329,7 +329,9 @@ void AppListButton::OnVoiceInteractionStatusChanged(
     case mojom::VoiceInteractionState::NOT_READY:
       // If we are showing the bursting or waiting animation, no need to do
       // anything. Otherwise show the waiting animation now.
-      if (!assistant_overlay_->IsBursting() &&
+      // NOTE: No waiting animation for native assistant.
+      if (!chromeos::switches::IsAssistantEnabled() &&
+          !assistant_overlay_->IsBursting() &&
           !assistant_overlay_->IsWaiting()) {
         assistant_overlay_->WaitingAnimation();
       }