effects/overview: Properly map the windowHeap geometry

In https://invent.kde.org/plasma/kwin/-/merge_requests/6747
the comparison with window heap geometry was done with the
heap x/y/width/height properties to detect if the drop was done
off the heap, but this is wrong, because in Overview
window heaps are positioned with Translation transforms, so
we need to properly mapping its geometry with mapToItem
which is transforms aware

src/plugins/private/qml/WindowHeapDelegate.qml

@@ -149,6 +149,9 @@ ExpoCell {
             }
             function restoreDND(oldGlobalRect: rect) {
                 const newGlobalRect = mapFromItem(null, oldGlobalRect);
+                // We need proper mapping for the heap geometry becuase they are positioned with
+                // translation transformations
+                const heapRect = thumb.windowHeap.mapToItem(null, Qt.size(thumb.windowHeap.width, thumb.windowHeap.height));
                 // Disable bindings
                 returnAnimation.active = true;
                 x = newGlobalRect.x;
@@ -159,10 +162,10 @@ ExpoCell {
                 returnAnimation.restart();
 
                 // If we dropped on another desktop, don't make the window fly off  the screen
-                if (newGlobalRect.x < thumb.windowHeap.x ||
-                    newGlobalRect.y < thumb.windowHeap.y ||
-                    thumb.windowHeap.x + thumb.windowHeap.width < newGlobalRect.x + newGlobalRect.width ||
-                    thumb.windowHeap.y + thumb.windowHeap.height < newGlobalRect.y + newGlobalRect.height) {
+                if (oldGlobalRect.x < heapRect.x ||
+                    oldGlobalRect.y < heapRect.y ||
+                    heapRect.x + heapRect.width < oldGlobalRect.x + oldGlobalRect.width ||
+                    heapRect.y + heapRect.height < oldGlobalRect.y + oldGlobalRect.height) {
                     returnAnimation.complete();
                 }
             }