Save all vertical alignment values in the old kspread file format.

The old file format is still use for clipboard storage, so this bug
meant middle aligned formatting wasn't properly copy/pasted.

BUG: 335100

sheets/Style.cpp

@@ -1499,7 +1499,7 @@ void Style::saveXML(QDomDocument& doc, QDomElement& format, const StyleManager*
     if (keysToStore.contains(HorizontalAlignment) && halign() != HAlignUndefined)
         format.setAttribute(type() == AUTO ? "align" : "alignX", (int) halign());
 
-    if (keysToStore.contains(VerticalAlignment) && valign() != Middle)
+    if (keysToStore.contains(VerticalAlignment) && valign() != VAlignUndefined)
         format.setAttribute("alignY", (int) valign());
 
     if (keysToStore.contains(BackgroundColor) && backgroundColor().isValid())