Utils: Remove unused TreeWidget class

Static QTreeWidgets are often clumsy to use and typically not what
we want to promote.

Change-Id: Ib7fa8172a60aad61508e118a93c0317b726efc13
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/utils/itemviews.cpp

@@ -86,12 +86,6 @@ void TreeView::setSearchRole(int role)
     makeViewSearchable(this, role);
 }
 
-TreeWidget::TreeWidget(QWidget *parent)
-    : View<QTreeWidget>(parent)
-{
-    setUniformRowHeights(true);
-}
-
 ListView::ListView(QWidget *parent)
     : View<QListView>(parent)
 {}

src/libs/utils/itemviews.h

@@ -86,12 +86,6 @@ public:
     void setSearchRole(int role);
 };
 
-class QTCREATOR_UTILS_EXPORT TreeWidget : public View<QTreeWidget>
-{
-public:
-    TreeWidget(QWidget *parent = nullptr);
-};
-
 class QTCREATOR_UTILS_EXPORT ListView : public View<QListView>
 {
 public: