Wizards: Remove unused QtQuick.Controls-style preview thumbnails

These were never used. And updated ones are upcoming with the new QDS
application wizards.

Change-Id: I998c3c0b8cfa3033d8be46524db3ed978738e729
Reviewed-by: Artem Sokolovskii <artem.sokolovskii@qt.io>
Reviewed-by: Samuel Ghinet <samuel.ghinet@qt.io>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/projectexplorer/jsonwizard/jsonwizard_test.cpp

@@ -270,7 +270,7 @@ void ProjectExplorer::ProjectExplorerPlugin::testJsonWizardsIconList()
         QJsonObject{
            {"trKey", "item no1"},
            {"condition", true},
-           {"icon", iconInsideResource("templates/wizards/qtquickstyleicons/default.png")}
+           {"icon", iconInsideResource("templates/wizards/global/lib.png")}
         },
         QJsonObject{
            {"trKey", "item no2"},
@@ -282,7 +282,7 @@ void ProjectExplorer::ProjectExplorerPlugin::testJsonWizardsIconList()
             {"trKey", "item no3"},
             {"condition", true},
             {"trToolTip", "MyToolTip"},
-            {"icon", iconInsideResource("templates/wizards/qtquickstyleicons/default.png")}
+            {"icon", iconInsideResource("templates/wizards/global/lib.png")}
         }
     });
 

src/tools/iconlister/iconlister.cpp

@@ -1081,16 +1081,6 @@ void IconLister::addWizardIcons()
          ""},
         {QIcon(wizardsPath + "projects/vcs/subversion/icon.png"), "subversion_vcs", prefix,
          ""},
-        {QIcon(wizardsPath + "qtquickstyleicons/default.png"), "default_qtquickstyle", prefix,
-         ""},
-        {QIcon(wizardsPath + "qtquickstyleicons/material-dark.png"), "material-dark_qtquickstyle", prefix,
-         ""},
-        {QIcon(wizardsPath + "qtquickstyleicons/material-light.png"), "material-light_qtquickstyle", prefix,
-         ""},
-        {QIcon(wizardsPath + "qtquickstyleicons/universal-dark.png"), "universal-dark_qtquickstyle", prefix,
-         ""},
-        {QIcon(wizardsPath + "qtquickstyleicons/universal-light.png"), "universal-light_qtquickstyle", prefix,
-         ""},
     };
     m_icons.append(icons);
 }