Revert "desks: Fix unnecessary highlight on disabled new desk button."

This reverts commit 619a3f3e.

Reason for revert: suspected to break ash_unittests on MSAN: https://findit-for-me.appspot.com/waterfall/failure?url=https://build.chromium.org/p/chromium.memory/builders/Linux%20ChromiumOS%20MSan%20Tests/builds/14981

Original change's description:
> desks: Fix unnecessary highlight on disabled new desk button.
> 
> Test: manual
> Bug: 1000191
> Change-Id: Iad3e0918ae6c82e3939e0e9413d93b0f58c2eda5
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1782671
> Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
> Commit-Queue: Sammie Quon <sammiequon@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#692794}

TBR=afakhry@chromium.org,sammiequon@chromium.org

Change-Id: I4baf70a77f62b2880aaeca4d5b3b7d4aca9aa51f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1000191
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1782360Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692936}

ash/wm/desks/new_desk_button.cc

@@ -168,7 +168,7 @@ void NewDeskButton::OnViewUnhighlighted() {
 }
 
 void NewDeskButton::UpdateBorderState() {
-  if (IsViewHighlighted() && DesksController::Get()->CanCreateDesks()) {
+  if (IsViewHighlighted()) {
     SetBorder(views::CreateRoundedRectBorder(
         kHighlightThicknessDp, kCornerRadius,
         GetNativeTheme()->GetSystemColor(

ash/wm/overview/overview_highlight_controller.cc

@@ -260,7 +260,6 @@ void OverviewHighlightController::OnViewDestroyingOrDisabling(
   DCHECK_GE(current_index, 0);
   deleted_index_ = base::make_optional(current_index);
   highlight_widget_.reset();
-  highlighted_view_->OnViewUnhighlighted();
   highlighted_view_ = nullptr;
 }