[applets/taskmanager] Don't show icons on top of thumbnails on Wayland

BUG: 427076
FIXED-IN: 5.20

applets/taskmanager/package/contents/ui/ToolTipInstance.qml

@@ -230,7 +230,7 @@ ColumnLayout {
             source: thumbnailSourceItem.isMinimized && !albumArtImage.visible && Number.isInteger(thumbnailSourceItem.winId) ? icon : ""
             animated: false
             usesPlasmaTheme: false
-            visible: valid
+            visible: valid && !pipeWireLoader.active
         }
 
         ToolTipWindowMouseArea {