wallpaper/slideshow: shouldn't display "current" item in image list

In the config dialog of slideshow wallpaper, the first image is always in a "current selected" state (thick, deep blue border). And it can't change with neither mouse click or keyboard.

Slideshow has no such thing as "current", so this effect should be removed.

BUG: 457327

![Screenshot_20220731_112227](/uploads/73be3edcb45ac3a1ef5c92b26f6cf46e/Screenshot_20220731_112227.jpg)


(cherry picked from commit 01defdb573)

wallpapers/image/imagepackage/contents/ui/ThumbnailsComponent.qml

@@ -26,7 +26,9 @@ Item {
         function resetCurrentIndex() {
             //that min is needed as the module will be populated in an async way
             //and only on demand so we can't ensure it already exists
-            view.currentIndex = Qt.binding(() =>  Math.min(imageModel.indexOf(cfg_Image), imageModel.count - 1));
+            if (configDialog.currentWallpaper === "org.kde.image") {
+                view.currentIndex = Qt.binding(() =>  Math.min(imageModel.indexOf(cfg_Image), imageModel.count - 1));
+            }
         }
 
         //kill the space for label under thumbnails