Revert "Enable Assistant launcher UI feature flag by default"

This reverts commit 7f5baf23.

Reason for revert: It's likely a culprit for HomeButtonTest.LongPressGesture failure. Here is the first failure https://ci.chromium.org/p/chromium/builders/ci/Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20%281%29/36138?blamelist=1#blamelist-tab

Original change's description:
> Enable Assistant launcher UI feature flag by default
> 
> Bug: b/144383302
> Test: Manual Test
> Change-Id: I50a2462e2094d08d52141a626c0dad89d55d27c0
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1915322
> Commit-Queue: Yue Li <updowndota@chromium.org>
> Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
> Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#715971}

TBR=xiyuan@chromium.org,xiaohuic@chromium.org,updowndota@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: b/144383302
Change-Id: Ib29930d141e1e9ad23c92f5a06fa7ac5ae572a54
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1917215Reviewed-by: Vadym Doroshenko <dvadym@chromium.org>
Commit-Queue: Vadym Doroshenko <dvadym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#716108}

ash/app_list/views/assistant/assistant_page_view.cc

@@ -206,6 +206,8 @@ void AssistantPageView::OnShown() {
 
 void AssistantPageView::OnAnimationStarted(AppListState from_state,
                                            AppListState to_state) {
+  if (to_state != AppListState::kStateEmbeddedAssistant)
+    return;
   UpdatePageBoundsForState(to_state, contents_view()->GetContentsBounds(),
                            contents_view()->GetSearchBoxBounds(to_state));
 }

ash/assistant/ui/assistant_container_view_unittest.cc

@@ -8,7 +8,6 @@
 
 #include "ash/assistant/assistant_controller.h"
 #include "ash/assistant/assistant_ui_controller.h"
-#include "ash/public/cpp/app_list/app_list_features.h"
 #include "ash/session/session_controller_impl.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
@@ -31,10 +30,6 @@ class AssistantContainerViewTest : public AshTestBase {
   ~AssistantContainerViewTest() override = default;
 
   void SetUp() override {
-    // Disable the launcher UI feature flag to test the container view.
-    feature_list_.InitAndDisableFeature(
-        app_list_features::kEnableAssistantLauncherUI);
-
     AshTestBase::SetUp();
 
     // Cache controller.
@@ -57,7 +52,6 @@ class AssistantContainerViewTest : public AshTestBase {
   AssistantUiController* ui_controller() { return ui_controller_; }
 
  private:
-  base::test::ScopedFeatureList feature_list_;
   AssistantController* controller_ = nullptr;
   AssistantUiController* ui_controller_ = nullptr;
 

ash/public/cpp/app_list/app_list_features.cc

@@ -40,7 +40,7 @@ const base::Feature kEnableAppReinstallZeroState{
 const base::Feature kEnableAssistantSearch{"EnableEmbeddedAssistantUI",
                                            base::FEATURE_DISABLED_BY_DEFAULT};
 const base::Feature kEnableAssistantLauncherUI{
-    "EnableAssistantLauncherUI", base::FEATURE_ENABLED_BY_DEFAULT};
+    "EnableAssistantLauncherUI", base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kEnableAppGridGhost{"EnableAppGridGhost",
                                         base::FEATURE_DISABLED_BY_DEFAULT};