[applets/systemtray] Fix icon hitboxes being too big in 2 row/column view

They were always calculating the size as if there was one row or column,
even if there were actually two.

BUG: 424812

applets/systemtray/package/contents/ui/main.qml

@@ -43,7 +43,7 @@ MouseArea {
 
     // Used only by AbstractItem, but it's easiest to keep it here since it
     // uses dimensions from this item to calculate the final value
-    readonly property int itemSize: autoSize ? units.roundToIconSize(Math.min(Math.min(width, height), units.iconSizes.enormous)) : smallIconSize
+    readonly property int itemSize: autoSize ? units.roundToIconSize(Math.min(Math.min(width / rowsOrColumns, height / rowsOrColumns), units.iconSizes.enormous)) : smallIconSize
 
     // The rest are derived properties; do not modify
     readonly property bool vertical: plasmoid.formFactor === PlasmaCore.Types.Vertical