QmlDesigner: Do not set size

Setting the icon size will lead to the icon font being used
in Qt 6.7.3. We would have to set the complete font object.

Change-Id: Ie770416c4a6c55c08259fce29367c59af17cf8ba
Reviewed-by: Henning Gründl <henning.gruendl@qt.io>

share/qtcreator/qmldesigner/newprojectdialog/imports/NewProjectDialog/Details.qml

@@ -440,7 +440,7 @@ Item {
                 width: StudioTheme.Values.singleControlColumnWidth
                 buttonIcon: qsTr("Save Custom Preset")
                 iconFont: StudioTheme.Constants.font
-                iconSize: DialogValues.defaultPixelSize
+
                 anchors.bottom: parent.bottom
                 anchors.horizontalCenter: parent.horizontalCenter